CVE-2025-61672

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.

References

https://github.com/element-hq/synapse/security/advisories/GHSA-fh66-fcv5-jjfr

https://github.com/element-hq/synapse/releases/tag/v1.139.1

https://github.com/element-hq/synapse/releases/tag/v1.138.3

https://github.com/element-hq/synapse/pull/17097

https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919ef2740

https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d670034b3c1

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4

EPSS