CVE-2025-28859: Maintenance Notice Plugin CSRF Vulnerability

CVE-2025-28859 Overview

CVE-2025-28859 is a Cross-Site Request Forgery (CSRF) vulnerability in the CodeVibrant Maintenance Notice WordPress plugin. The flaw affects all versions up to and including 1.0.6. Attackers can exploit the issue to force authenticated administrators into performing unwanted state-changing actions on the plugin. Exploitation requires user interaction, such as clicking a malicious link or visiting a crafted page while authenticated to the target WordPress site. The vulnerability is tracked under CWE-352: Cross-Site Request Forgery and was published to the National Vulnerability Database on March 11, 2025.

Critical Impact

Successful exploitation allows attackers to modify plugin configuration on behalf of an authenticated administrator, leading to high-impact changes to site confidentiality, integrity, and availability.

Affected Products

• CodeVibrant Maintenance Notice WordPress plugin versions up to and including 1.0.6
• WordPress installations with the maintenance-notice plugin active
• Sites where administrators interact with attacker-controlled content while authenticated

Discovery Timeline

• 2025-03-11 - CVE-2025-28859 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-28859

Vulnerability Analysis

The Maintenance Notice plugin exposes one or more state-changing endpoints that do not validate the origin of incoming requests. The plugin fails to verify a WordPress nonce or equivalent anti-CSRF token before processing privileged actions. An attacker who tricks a logged-in administrator into visiting a malicious page can submit forged HTTP requests using the victim's session cookies. The browser automatically attaches authentication credentials, and the plugin processes the request as legitimate administrative activity.

Because the request executes with administrator privileges, the resulting configuration changes can disrupt site availability, alter content displayed to visitors, or chain into further attacks. The vulnerability requires no prior authentication on the attacker side and exploitation occurs over the network.

Root Cause

The root cause is missing CSRF protection on plugin request handlers, classified as [CWE-352]. The plugin does not call wp_verify_nonce() or check_admin_referer() on form submissions and administrative AJAX endpoints. Without nonce validation, the application cannot distinguish between requests intentionally initiated by the administrator and forged requests originating from a third-party site.

Attack Vector

Exploitation requires an authenticated WordPress administrator to interact with attacker-controlled content. An attacker hosts a page containing an HTML form or JavaScript that submits a request to the vulnerable plugin endpoint on the target WordPress site. When the victim visits the malicious page, the browser submits the forged request along with valid WordPress session cookies. The plugin executes the action because it does not validate the request token or referrer. Refer to the Patchstack WordPress Plugin Advisory for additional technical details.

Detection Methods for CVE-2025-28859

Indicators of Compromise

• Unexpected configuration changes to the Maintenance Notice plugin settings without corresponding administrator activity in WordPress audit logs
• HTTP POST or GET requests to plugin endpoints with Referer headers pointing to external, untrusted domains
• Maintenance mode toggling or notice content modifications occurring outside scheduled change windows
• WordPress administrator sessions accessing the wp-admin area concurrently with unusual outbound link clicks in browser history

Detection Strategies

• Monitor WordPress access logs for requests to maintenance-notice plugin endpoints that lack a same-origin Referer header
• Deploy a Web Application Firewall (WAF) rule that flags state-changing requests to the plugin without a valid _wpnonce parameter
• Correlate administrator authentication events with subsequent plugin configuration changes to identify timing anomalies
• Enable WordPress activity logging plugins to capture plugin option changes and the originating IP address

Monitoring Recommendations

• Track changes to WordPress wp_options rows associated with the Maintenance Notice plugin
• Alert on HTTP requests where the Origin header does not match the WordPress site domain on plugin endpoints
• Review administrator browser activity logs after any unexplained maintenance notice changes

How to Mitigate CVE-2025-28859

Immediate Actions Required

• Identify all WordPress sites running the CodeVibrant Maintenance Notice plugin at version 1.0.6 or earlier
• Deactivate and remove the plugin if a patched version is not yet available for your environment
• Restrict administrator browsing habits and require administrators to use dedicated browsers or profiles for wp-admin sessions
• Apply WAF rules that enforce nonce validation on requests to the maintenance-notice plugin paths

Patch Information

No patched version is identified in the available advisory data. The Patchstack advisory lists all versions up to and including 1.0.6 as vulnerable. Administrators should monitor the Patchstack WordPress Plugin Advisory and the WordPress plugin repository for a fixed release that adds nonce verification to all state-changing endpoints.

Workarounds

• Uninstall the Maintenance Notice plugin and replace it with an alternative that implements CSRF protection
• Configure a WAF or reverse proxy to drop requests to plugin endpoints lacking a valid _wpnonce parameter and same-origin Referer header
• Enforce SameSite=Strict or SameSite=Lax cookie attributes on WordPress authentication cookies to limit cross-site request submission
• Require administrators to log out of WordPress sessions when not actively managing the site to shrink the exploitation window

# Configuration example: Apache mod_security rule to block CSRF on plugin endpoint
SecRule REQUEST_URI "@contains /wp-admin/admin.php" \
    "chain,deny,status:403,id:1002859,msg:'Possible CSRF on Maintenance Notice plugin'"
SecRule ARGS:page "@streq maintenance-notice" "chain"
SecRule &ARGS:_wpnonce "@eq 0"