CVE-2025-31735 Overview
CVE-2025-31735 is a stored cross-site scripting (XSS) vulnerability in the C. Johnson Footnotes for WordPress plugin (footnotes-for-wordpress). The flaw affects all plugin versions up to and including 2016.1230. Authenticated users with sufficient privileges can inject malicious script payloads that persist in plugin-generated output. When other users or administrators view affected pages, the browser executes the stored script in their session context. The issue is categorized under CWE-79, Improper Neutralization of Input During Web Page Generation.
Critical Impact
Stored XSS payloads persist across sessions, enabling session hijacking, credential theft, and administrative account takeover on affected WordPress sites.
Affected Products
- C. Johnson Footnotes for WordPress plugin (footnotes-for-wordpress)
- All versions from n/a through 2016.1230
- WordPress installations with the plugin activated
Discovery Timeline
- 2025-04-01 - CVE-2025-31735 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-31735
Vulnerability Analysis
The Footnotes for WordPress plugin fails to sanitize or encode user-supplied input before rendering it in web pages. The plugin accepts footnote content from authenticated contributors and stores it in the WordPress database. When pages containing footnotes render, the plugin outputs the stored content without applying proper output encoding.
Attackers with author-level or contributor-level access can embed JavaScript within footnote fields. The payload persists in the database and executes each time a visitor renders the affected content. Successful exploitation runs arbitrary JavaScript under the victim's origin, enabling cookie theft, forced actions via CSRF, and pivot into administrative functionality.
Exploitation requires low-privilege authentication and user interaction to view the poisoned page. The scope change means the injected script executes across security boundaries, affecting authenticated administrators who visit compromised content.
Root Cause
The root cause is missing input sanitization and output escaping in the plugin's footnote handling logic. WordPress provides functions such as wp_kses_post() and esc_html() for this purpose, but the plugin does not invoke them consistently when storing or emitting footnote content. This violates the guidance in the WordPress Plugin Handbook regarding data validation.
Attack Vector
The attack vector is network-based and requires an authenticated account with the ability to author or edit posts. The attacker submits a footnote containing an HTML or JavaScript payload through a standard WordPress editor. The payload is stored, and any subsequent viewer of the containing post triggers execution. No specialized tooling is required; a standard browser is sufficient. Refer to the Patchstack XSS Vulnerability Report for additional context on the injection surface.
Detection Methods for CVE-2025-31735
Indicators of Compromise
- Post or page content containing <script>, onerror=, onload=, or javascript: sequences within footnote fields.
- Unexpected outbound requests from browser sessions of administrators viewing plugin-rendered pages.
- New or modified WordPress administrator accounts created shortly after a low-privileged user edited posts.
- Database entries in wp_posts or plugin-specific tables containing encoded HTML event handlers.
Detection Strategies
- Query the WordPress database for footnote content matching common XSS token patterns.
- Enable web application firewall (WAF) rules that inspect post submissions for script tags and event handlers.
- Review plugin version inventory across managed WordPress sites and flag any installation at or below 2016.1230.
- Correlate contributor or author account activity with subsequent administrator session anomalies.
Monitoring Recommendations
- Log all wp-admin/post.php and post-new.php submissions and alert on payloads containing HTML tags in footnote parameters.
- Monitor Content Security Policy (CSP) violation reports for inline script execution on plugin-rendered pages.
- Track privilege changes and new user creation events in the WordPress audit log after suspicious content edits.
How to Mitigate CVE-2025-31735
Immediate Actions Required
- Deactivate and remove the Footnotes for WordPress plugin until a patched version is confirmed available.
- Audit all existing posts and pages for previously injected footnote payloads and remove malicious content.
- Rotate credentials and session tokens for administrator accounts that may have viewed compromised pages.
- Review recent user role changes and revert unauthorized privilege escalations.
Patch Information
No vendor patch is referenced in the NVD entry as of the last modification date. The plugin has not received an update beyond version 2016.1230. Site owners should treat the plugin as abandoned and migrate to a maintained footnote alternative. Consult the Patchstack advisory for the latest remediation status.
Workarounds
- Restrict content authoring privileges to trusted users only, minimizing the pool of accounts able to inject footnotes.
- Deploy a WAF rule set that blocks script tags and event handler attributes in post submissions.
- Enforce a strict Content Security Policy that disallows inline JavaScript on WordPress-rendered pages.
- Replace the plugin with an actively maintained footnote solution that sanitizes input using wp_kses_post().
# Configuration example: disable the vulnerable plugin via WP-CLI
wp plugin deactivate footnotes-for-wordpress
wp plugin delete footnotes-for-wordpress
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
