# CVE-2026-52778

## Summary

- **CVE ID:** CVE-2026-52778
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** CWE-94, CWE-1333
- **Published:** Jun 8, 2026
- **Last Modified:** Jun 9, 2026

## 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 — yeswiki (< 4.6.6)

## References

- [CNA](https://github.com/YesWiki/yeswiki/security/advisories/GHSA-px5m-h76g-p7p8)
- [CNA](https://github.com/YesWiki/yeswiki/commit/dd2bd8fb099de0d21504bda8a810693b3fcb8e52)
- [CNA](https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.56%
- **EPSS Percentile:** 44.9

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._