CVE-2026-73321
mediumXenForo before 2.3.13 contains an uncontrolled recursion vulnerability in the BBCode parser that allows authenticated attackers to cause persistent denial of s…
Vendor / product: Xenforo — xenforo
XenForo before 2.3.13 contains an uncontrolled recursion vulnerability in the BBCode parser that allows authenticated attackers to cause persistent denial of service by submitting a post with deeply nested BBCode tags. Attackers can craft a single malicious post with sufficient nesting depth to exceed PHP's stack limit, causing fatal errors that repeatedly terminate PHP-FPM workers for all visitors rendering the affected thread.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Affected products
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
No vendor advisory or patch reference tagged by NVD. Check the references below.
References
- https://bombobombone.github.io/posts/cve-2026-73321/ disclosure@vulncheck.com
- https://github.com/BomboBombone/CVE-2026-73321 disclosure@vulncheck.com
- https://www.vulncheck.com/advisories/xenforo-uncontrolled-recursion-dos-via-bbcode-parser disclosure@vulncheck.com
- https://xenforo.com/community/threads/security-fixes-released-for-all-xenforo-and-media-ga... disclosure@vulncheck.com
- https://xenforo.com/community/threads/xenforo-2-3-13-and-add-ons-released-includes-securit... disclosure@vulncheck.com