CVE-2026-104454: YesWiki before 4.6.7 ReDoS via wakka.php Edit-Preview Endpoint

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-02 · updated 2026-10-02
Weakness: CWE-1333

Description

YesWiki before 4.6.7 contains an algorithmic-complexity denial of service in the wakka.php formatter due to an O(n^2) markdown-link regex. Unauthenticated attackers can submit a small crafted body of bracket characters to the page-edit preview endpoint to pin PHP-FPM workers and saturate the pool.

Affected products

yeswiki: before 4.6.7 — fixed in 4.6.7

How to fix

Upgrade to a fixed version: yeswiki 4.6.7. Check the vendor advisory for mitigations.

References

https://github.com/YesWiki/yeswiki/security/advisories/GHSA-gf57-wg5m-h34q
https://www.vulncheck.com/advisories/yeswiki-before-4.6.7-redos-via-wakka-php-edit-preview-endpoint
https://github.com/YesWiki/yeswiki/security/advisories/GHSA-gf57-wg5m-h34q

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