Kyrias

**Name of the Vulnerable Software and Affected Versions** Matrix Synapse versions prior to 1.5.0 **Description** The issue concerns the mishandling of signature checking on some federation APIs. Events sent over "/send join", "/send leave", and "/invite" API endpoints may not be correctly signed, or may not come from the expected servers. **Recommendations** For Matrix Synapse versions prior to 1.5.0, update to version 1.5.0 or later to resolve the issue. As a temporary workaround, consider restricting access to the "/send join", "/send leave", and "/invite" API endpoints to minimize the risk of exploitation.