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CRITICAL

CVE-2026-52778

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

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.

Published Updated Sources: cvelistV5, GitHub_M

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Unreported

no source claims exploitation

EPSS

1%

chance of exploitation in 30 days

Affects

yeswiki

yeswiki

CVSS base

9.8

CRITICAL

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

PoC

none · proof-of-concept · active

Automatable

Yes

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Affected scope

The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.

Vendors (1)

yeswiki

Products (1)

yeswiki

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactSource
9.8CVSS 3.1CRITICAL——cvelistV5

Weakness & attack patterns

  • CWE-94
  • CWE-1333

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

  • T1027.006Obfuscated Files or Information: HTML Smuggling
  • T1027.009Obfuscated Files or Information: Embedded Payloads
  • T1564.009Hide Artifacts: Resource Forking

References

3 on the record

Elsewhere on this site

  • yeswikievery CVE for this vendor
  • CWE-94other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.