What’s Vulnerable › Vulnerabilities

CVE-2026-52778: YesWiki has Unsafe eval() in Formula Calculator - Remote Code Execution (RCE) & Denial of Service (DoS)

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-08 · updated 2026-10-06
• Weakness: CWE-94

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.

Affected products

• yeswiki: before 4.6.6

References

• https://github.com/YesWiki/yeswiki/commit/dd2bd8fb099de0d21504bda8a810693b3fcb8e52
• 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

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