CVE-2026-52778Critical· 9.8▾ MidnightYesWiki 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 formu…
▾ Midnight zone — Critical, or high with PoC / in-the-wild
impact 53.9 · likelihood 0.2 · exploitation 0
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Exploit-prediction probability, daily snapshots since Aug 3.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.6%
0.6% → 0.9%
Last analysed / modified upstream
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.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
yeswiki/yeswiki < 4.6.6Patched in:
yeswiki/yeswiki 4.6.6Connected by shared product, vendor, weakness, or advisory.
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