Vulnerability Description
Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to degrade federation functionality, unpredictably breaking outbound federation to other homeservers. The issue is patched in Synapse 1.138.3, 1.138.4, 1.139.1, and 1.139.2. Note that even though 1.138.3 and 1.139.1 fix the vulnerability, they inadvertently introduced an unrelated regression. For this reason, the maintainers of Synapse recommend skipping these releases and upgrading straight to 1.138.4 and 1.139.2.
Related Weaknesses (CWE)
References
- https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d67003
- https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919e
- https://github.com/element-hq/synapse/pull/17097
- https://github.com/element-hq/synapse/releases/tag/v1.138.3
- https://github.com/element-hq/synapse/releases/tag/v1.139.1
- https://github.com/element-hq/synapse/security/advisories/GHSA-fh66-fcv5-jjfr
FAQ
What is CVE-2025-61672?
CVE-2025-61672 is a documented vulnerability. Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to...
How severe is CVE-2025-61672?
CVSS scoring is not yet available for CVE-2025-61672. Check NVD for updates.
Is there a patch for CVE-2025-61672?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.