CVE-2025-13857: Critical XSS Flaw Exposes WordPress Sites Using Yet Another WebClap

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Overview

CVE-2025-13857 identifies a Stored Cross-Site Scripting (XSS) vulnerability affecting the “Yet Another WebClap for WordPress” plugin. This vulnerability allows authenticated attackers with Contributor-level access or higher to inject malicious JavaScript code into WordPress pages or posts. This code will then execute whenever a user views the affected page, potentially leading to account compromise, data theft, or defacement of the website.

Technical Details

The vulnerability resides in the handling of the ‘text’ parameter within the webclap_button shortcode of the plugin. Due to insufficient input sanitization and output escaping, an attacker can inject arbitrary HTML and JavaScript code through this parameter. Specifically, versions up to and including 0.2 of the plugin are affected. The vulnerable code resides in yawebclap.php. An authenticated user with contributor access can create a post/page containing a webclap shortcode with a malicious ‘text’ attribute, such as:

[webclap_button text="<script>alert('XSS Vulnerability');</script>"]

When a user views this page, the injected JavaScript code will execute in their browser.

CVSS Analysis

  • CVSS Score: 6.4 (Medium)
  • Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
  • Explanation: This score reflects the fact that the vulnerability requires authentication and user interaction, but can lead to code execution in the user’s browser within the context of the vulnerable website. The impact is limited to confidentiality and integrity, with no impact on availability.

Possible Impact

Successful exploitation of this vulnerability can have significant consequences:

  • Account Takeover: An attacker can steal a user’s session cookie and impersonate them, potentially gaining administrative access.
  • Data Theft: Sensitive information, such as personal details or financial data, can be stolen.
  • Website Defacement: The attacker can modify the content and appearance of the website.
  • Malware Distribution: The attacker can inject malicious scripts that redirect users to phishing sites or distribute malware.

Mitigation or Patch Steps

The most effective mitigation is to:

  • Update the Plugin: Upgrade to a patched version of the “Yet Another WebClap for WordPress” plugin as soon as it becomes available. Check the WordPress plugin repository for updates. If no update is available immediately…
  • Disable the Plugin: If an update is not available, temporarily disable the “Yet Another WebClap for WordPress” plugin until a patch is released. This will prevent exploitation of the vulnerability.
  • Implement Input Sanitization (if possible): If you have the technical expertise, you can manually sanitize the input of the ‘text’ parameter in the webclap_button shortcode. However, this is not recommended unless you are confident in your ability to do so securely. Make sure to properly escape the output.

References

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