CVE-2025-9880 Overview
CVE-2025-9880 is a Cross-Site Request Forgery (CSRF) vulnerability affecting the Side Slide Responsive Menu plugin for WordPress in all versions up to and including 1.0. The flaw stems from missing or incorrect nonce validation on a plugin function. Unauthenticated attackers can exploit this weakness to update plugin settings and inject malicious web scripts. Exploitation requires tricking a site administrator into clicking a crafted link or visiting an attacker-controlled page. The vulnerability is classified under [CWE-352] and carries a medium severity rating.
Critical Impact
Successful exploitation allows attackers to alter plugin settings and inject stored scripts that execute in administrator or visitor browsers, enabling session theft, redirection, or defacement of affected WordPress sites.
Affected Products
- Side Slide Responsive Menu plugin for WordPress
- All versions up to and including 1.0
- WordPress sites with the vulnerable plugin activated
Discovery Timeline
- 2025-09-12 - CVE-2025-9880 published to the National Vulnerability Database (NVD)
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-9880
Vulnerability Analysis
The Side Slide Responsive Menu plugin exposes an administrative settings function that does not verify a valid WordPress nonce token before processing state-changing requests. WordPress nonces are the framework's built-in mechanism for validating that a request originated from a legitimate user session. When this check is absent or improperly implemented, the browser will still attach the administrator's authentication cookies to any request the browser issues, including cross-origin requests initiated from attacker-controlled pages.
Because the vulnerable handler also fails to sanitize the input it stores, the attacker can combine the CSRF with script injection. The injected payload is written to plugin configuration and rendered on subsequent page loads, effectively turning a one-time forged request into persistent stored Cross-Site Scripting (XSS).
Root Cause
The root cause is missing or incorrect nonce validation in the plugin's settings update handler, as tracked in SideSlideMenu.class.php and sideslide_admin.php. The handler does not call check_admin_referer() or wp_verify_nonce() against a request-bound token, so any authenticated administrator request reaching the endpoint is accepted regardless of origin.
Attack Vector
An attacker crafts a malicious HTML page or link containing an auto-submitting form or fetch request targeting the plugin's admin endpoint. The attacker delivers the link through phishing, forum posts, or comments. When an authenticated site administrator loads the attacker's page, the browser submits the forged request with valid session cookies. The plugin accepts the request, updates settings, and stores the attacker's script payload for later execution.
No authentication is required from the attacker, but the attack requires user interaction from a privileged victim.
Detection Methods for CVE-2025-9880
Indicators of Compromise
- Unexpected modifications to Side Slide Responsive Menu plugin settings in the WordPress wp_options table
- Presence of <script> tags, javascript: URIs, or event handlers within plugin configuration values
- Administrator sessions showing outbound requests to unfamiliar domains immediately before settings changes
- Referer headers in web server logs pointing to external domains for requests hitting plugin admin endpoints
Detection Strategies
- Review WordPress audit logs for plugin option changes that lack a corresponding admin console navigation trail
- Inspect rendered menu HTML on public pages for injected script content or unexpected inline JavaScript
- Correlate administrator authentication events with settings-modification requests originating from external referers
- Scan the plugin source in wp-content/plugins/side-slide-responsive-menu/ for missing wp_verify_nonce or check_admin_referer calls in POST handlers
Monitoring Recommendations
- Alert on POST requests to plugin admin URLs where the Referer header is empty or off-domain
- Monitor WordPress database changes to plugin-owned rows in wp_options and flag unexpected writes
- Track administrator account activity for signs of session abuse following clicks on external links
- Log and review Content Security Policy (CSP) violation reports for injected script sources
How to Mitigate CVE-2025-9880
Immediate Actions Required
- Deactivate and remove the Side Slide Responsive Menu plugin until a patched version is published
- Audit plugin settings and menu configuration for any injected script content and restore known-good values
- Force-rotate administrator passwords and invalidate active sessions if compromise is suspected
- Review the Wordfence Vulnerability Report for the latest fix status
Patch Information
At the time of publication, no fixed version of the Side Slide Responsive Menu plugin is available. Versions up to and including 1.0 remain vulnerable. Site owners should monitor the WordPress Plugin Page for an updated release that adds nonce validation and output sanitization to the affected handler.
Workarounds
- Restrict access to /wp-admin/ using IP allowlisting or a Web Application Firewall (WAF) rule that blocks cross-origin POSTs
- Apply a WAF rule to reject requests to plugin admin endpoints missing a same-origin Referer header
- Enforce a strict Content Security Policy that disallows inline scripts on administrative pages
- Limit the number of administrator accounts and require administrators to use isolated browser profiles for WordPress management
# Configuration example: disable the vulnerable plugin via WP-CLI
wp plugin deactivate side-slide-responsive-menu
wp plugin delete side-slide-responsive-menu
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
