Certification ID: PSC-2025-64591 | Verified by CleanTalk Security Audit
The Plugin Security Certification (PSC-2025-64591) highlights a previously identified WordPress nonce validation issue, discovered and patched during internal security testing in March 2025. Developers can fix WordPress nonce error by ensuring every form submission includes proper PHP nonce checks using wp_nonce_field() and wp_verify_nonce().
The report documented inconsistent CSRF nonce checks that, under specific conditions, could allow unauthorized user actions or cached session exploits.
CleanTalk addressed the issue and reaffirmed its commitment to plugin security through the Plugin Security Certification (PSC).
What Was Affected
During routine evaluation, researchers detected irregular nonce verification patterns in several WordPress plugins.
Although no active exploits occurred, the validation gap allowed a potential path for session hijacking or unauthorized operations under certain cached states.
Affected developers were advised to re-implement proper nonce validation using:
wp_nonce_field();
wp_verify_nonce();Certified Secure: GDPR Cookie Compliance 5.0.9
The GDPR Cookie Compliance plugin (v5.0.9) successfully passed CleanTalk’s Plugin Security Certification (PSC-2025-64591), confirming that all nonce checks and input validations follow WordPress security best practices.
This version was tested against:
- SQL Injection (SQLi)
- Cross-Site Scripting (XSS) — Stored & Reflected
- Cross-Site Request Forgery (CSRF)
- Authentication and Privilege Escalation vulnerabilities
- Insecure Dependency Usage
- Information Disclosure & Code Execution vectors
Result: Passed all PSC security tests and verified as safe after the nonce patch (March 2025).
Why It Matters
Nonce validation isn’t just a minor technical fix — it’s part of the broader security posture of WordPress plugins.
By maintaining proper token verification, developers protect users from CSRF attacks and session exploits.
CleanTalk’s Plugin Security Certification ensures that certified plugins like GDPR Cookie Compliance meet modern standards for both data privacy (GDPR, CCPA, DSGVO) and application security.
FAQ
Q: What does “nonce validation” mean in WordPress?
A: It’s a token system that prevents unauthorized form submissions and CSRF attacks.
Q: How can I check if my plugin uses secure nonces?
A: Verify that your forms include wp_nonce_field() and your handlers use wp_verify_nonce().
Q: Is this issue still active?
A: No — it was patched and verified as safe in March 2025.
Q: Which plugins are PSC-certified?
A: You can find all certified plugins — including GDPR Cookie Compliance v5.0.9 — in the CleanTalk Plugin Security Registry.
Summary
The PSC-2025-64591 advisory began as a nonce validation issue but evolved into a successful case study of proactive plugin security testing.
By implementing strict nonce verification and passing the CleanTalk certification process, GDPR Cookie Compliance proved not only its compliance with global privacy laws but also its resilience against exploitation.