Vulnerability Description
YesWiki is a wiki system written in PHP. Prior to version 4.6.6, an unsafe execution vulnerability exists in the Bazar form field calculator (CalcField.php) of YesWiki. The application attempts to sanitize user-defined mathematical formulas using a complex recursive regular expression before passing them to the PHP eval() function. This implementation is inherently flawed: it is vulnerable to Regular Expression Denial of Service (ReDoS / Stack Overflow) which can crash the server, and it creates a high-risk architecture where any logic bypass directly results in arbitrary PHP code execution. Version 4.6.6 patches the issue.
CVSS Score
CRITICAL
Related Weaknesses (CWE)
References
- https://github.com/YesWiki/yeswiki/commit/dd2bd8fb099de0d21504bda8a810693b3fcb8e
- https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6
- https://github.com/YesWiki/yeswiki/security/advisories/GHSA-px5m-h76g-p7p8
- https://github.com/YesWiki/yeswiki/security/advisories/GHSA-px5m-h76g-p7p8
FAQ
What is CVE-2026-52778?
CVE-2026-52778 is a vulnerability with a CVSS score of 9.8 (CRITICAL). YesWiki is a wiki system written in PHP. Prior to version 4.6.6, an unsafe execution vulnerability exists in the Bazar form field calculator (CalcField.php) of YesWiki. The application attempts to san...
How severe is CVE-2026-52778?
CVE-2026-52778 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-52778?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.