CVE-2025-31639 Overview
CVE-2025-31639 is a Cross-Site Request Forgery (CSRF) vulnerability affecting the themeton Spare WordPress theme in all versions up to and including 1.7. The flaw is categorized under [CWE-352] and allows attackers to trick authenticated users into performing unintended actions on the vulnerable site. Exploitation requires user interaction, typically achieved by luring a logged-in administrator to visit a crafted page or click a malicious link. The vulnerability carries limited integrity impact and no direct confidentiality or availability impact.
Critical Impact
Attackers can forge requests that execute privileged actions in the context of an authenticated Spare theme user, potentially altering theme configuration without consent.
Affected Products
- themeton Spare WordPress theme versions up to and including 1.7
- WordPress sites using the Spare theme without a patched release
- Any deployment relying on Spare theme administrative endpoints lacking CSRF token validation
Discovery Timeline
- 2025-05-16 - CVE-2025-31639 published to the National Vulnerability Database
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-31639
Vulnerability Analysis
The vulnerability stems from missing or improper anti-CSRF token validation within the Spare theme. WordPress themes typically expose administrative actions through admin-post.php or admin-ajax.php handlers. When these handlers process state-changing requests without verifying a nonce via wp_verify_nonce() or check_admin_referer(), an attacker-controlled origin can submit forged requests that the browser will authenticate using the victim's active session cookies.
The EPSS score for this issue is 0.174%, placing it in the 7.145 percentile for likelihood of exploitation observation. The attack requires network access and user interaction, but no privileges on the target application. Successful exploitation yields limited integrity impact, consistent with configuration or content modification rather than full account takeover.
Root Cause
The root cause is the absence of a valid CSRF token check on one or more state-changing request handlers exposed by the Spare theme. Without this validation, the server accepts any request that includes the victim's authentication cookies, regardless of the request origin.
Attack Vector
An attacker crafts a malicious web page containing an auto-submitting form or JavaScript that issues a request to the vulnerable Spare theme endpoint. When an authenticated Spare administrator visits the page, the browser sends the request along with valid session cookies. The server processes the request as if it originated from a legitimate administrative workflow. See the Patchstack WordPress Vulnerability Report for advisory details.
Detection Methods for CVE-2025-31639
Indicators of Compromise
- Unexpected changes to Spare theme options or configuration entries in the WordPress database
- Administrative POST requests to Spare theme endpoints with Referer headers pointing to external, untrusted domains
- Repeated cross-origin requests targeting admin-post.php or admin-ajax.php with theme-specific action parameters
Detection Strategies
- Review web server access logs for state-changing requests to Spare theme endpoints originating from unexpected referrers
- Audit WordPress options and theme mod tables for unauthorized modifications correlated with administrator browsing activity
- Enable request logging with full headers to identify absent or invalid _wpnonce parameters on privileged actions
Monitoring Recommendations
- Alert on POST requests to WordPress admin endpoints that lack a valid _wpnonce parameter
- Monitor for administrator session activity immediately following external referrer navigation events
- Track version metadata for the Spare theme across managed WordPress installations to identify unpatched instances
How to Mitigate CVE-2025-31639
Immediate Actions Required
- Identify all WordPress sites running the Spare theme at version 1.7 or earlier and prioritize them for remediation
- Restrict administrative access to trusted networks and enforce short session lifetimes for privileged accounts
- Instruct administrators to log out of WordPress before browsing untrusted sites and to use isolated browser profiles for admin work
Patch Information
No fixed version is identified in the referenced advisory at the time of publication. Consult the Patchstack WordPress Vulnerability Report for the latest vendor guidance and any subsequent theme releases addressing the issue.
Workarounds
- Deactivate the Spare theme and switch to a maintained alternative until a patched version is released
- Deploy a Web Application Firewall (WAF) rule that requires a valid _wpnonce parameter on all Spare theme administrative endpoints
- Enforce SameSite=Lax or SameSite=Strict cookie attributes on WordPress session cookies to reduce cross-origin exposure
# Configuration example - enforce SameSite cookies via WordPress configuration
# Add to wp-config.php
@ini_set('session.cookie_samesite', 'Strict');
# Example ModSecurity rule to block admin POSTs without a nonce
SecRule REQUEST_METHOD "@streq POST" \
"chain,id:1003152,phase:2,deny,status:403,msg:'Missing WP nonce on admin request'"
SecRule REQUEST_URI "@rx /wp-admin/(admin-post|admin-ajax)\.php" \
"chain"
SecRule &ARGS:_wpnonce "@eq 0"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
