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PatchSiren cyber security CVE debrief

CVE-2026-52778 YesWiki CVE debrief

A critical vulnerability (CVSS Score: 9.8) exists in YesWiki's Bazar form field calculator (CalcField.php) prior to version 4.6.6. The application attempts to sanitize user-defined mathematical formulas using a complex recursive regular expression before passing them to the PHP eval() function. However, this implementation is flawed, making it vulnerable to Regular Expression Denial of Service (ReDoS / Stack Overflow) and allowing for arbitrary PHP code execution. This vulnerability was patched in version 4.6.6.

Vendor
YesWiki
Product
Unknown
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-08
Original CVE updated
2026-07-23
Advisory published
2026-06-08
Advisory updated
2026-07-23

Who should care

Users of YesWiki versions prior to 4.6.6 should apply the patch immediately to prevent potential attacks.

Technical summary

The vulnerability exists in the Bazar form field calculator (CalcField.php) of YesWiki. The flawed implementation of a recursive regular expression for sanitizing user-defined mathematical formulas can lead to a Denial of Service (DoS) and allow for arbitrary PHP code execution.

Defensive priority

High

Recommended defensive actions

  • Apply the patch by updating to YesWiki version 4.6.6 or later.
  • Review and restrict user input to the Bazar form field calculator to prevent potential attacks.

Evidence notes

The vulnerability was patched in version 4.6.6. References: [ref-4](https://github.com/YesWiki/yeswiki/commit/dd2bd8fb099de0d21504bda8a810693b3fcb8e52), [ref-5](https://github.com/YesWiki/yeswiki/releases/tag/v4.6.6), [ref-6](https://github.com/YesWiki/yeswiki/security/advisories/GHSA-px5m-h76g-p7p8).

Sources and references

Verified primary and authoritative sources

  • CVE-2026-52778 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-52778

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-52778 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-52778

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.