GHSA-p4xx-m758-3hpx

TYPO3 CMS Webhooks Server Side Request Forgery

### Problem Webhooks are inherently vulnerable to Server-Side Request Forgery (SSRF), which can be exploited by adversaries to target internal resources (e.g., _localhost_ or other services on the local network). While this is not a vulnerability in TYPO3 itself, it may enable attackers to blindly access systems that would otherwise be inaccessible. An administrator-level backend user account is required to exploit this vulnerability. ### Solution Update to TYPO3 versions 12.4.31 LTS, 13.4.12 LTS that fix the problem described. > [!IMPORTANT] > > **Manual actions required** > > To mitigate potential SSRF risks via webhooks, it is recommended to explicitly allow access only to trusted hosts. This can be achieved by configuring the allowlist in `$GLOBALS['TYPO3_CONF_VARS']['HTTP']['allowed_hosts']['webhooks']`. > > If the allowlist is not defined or set to `null`, all requests will be allowed. > If the allowlist is an empty `array`, all requests will be blocked. > > By default, the factory setting allows all requests. This prevents existing webhooks from failing after upgrading to the affected TYPO3 versions. Administrators must configure this setting manually to enforce restrictions. ### Credits Thanks to the National Cyber Security Center (NCSC) of Switzerland for reporting this issue, and to TYPO3 core & security team member Benjamin Franzke for fixing it.