CVE-2026-77143: TYPO3 Extension Forum

High severity, CVSS 8.8. EPSS: 0.4% chance of exploitation in the next 30 days.

The frontend topic editing flow does not verify on the server side that the requesting visitor owns the topic being modified. As a result, a visitor who knows the identifier of a topic from the public forum can submit a modified update request for that topic directly and overwrite its content, without the application confirming ownership. Topic identifiers are visible in the public forum listing, and exploitation requires no privileged access or non-default configuration.

Affected products

• TYPO3 Extension Forum: from 6.0.0, before 6.2.4 (fixed in 6.2.4); from 5.0.0, before 5.0.1 (fixed in 5.0.1); before 4.0.4 (fixed in 4.0.4)

Published 2026-08-25. Last modified 2026-09-28.