CVE-2025-61672
Synapse's invalid device keys degrade federation functionality
Impact
### Impact 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. ### Patches 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, it is recommend to skip these releases and upgrading straight to 1.138.4 and 1.139.2. ### Workarounds The vulnerability can only be exploited by users registered on the victim homeserver.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | matrix-synapse | < 1.138.3 | 1.138.3 |
Affected products
| Product | Affected versions |
|---|---|
| Synapse | before 1.138.3 |
Versions were read from the advisory text. No structured product data has been published for this record yet.
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/element-hq/synapse/commit/26aaaf9e48fff80cf67a20c691c75d670034b3c1
- https://github.com/element-hq/synapse/commit/7069636c2d6d1ef2022287addf3ed8b919ef2740
- 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
- https://github.com/advisories/GHSA-fh66-fcv5-jjfr
- https://nvd.nist.gov/vuln/detail/CVE-2025-61672
- https://github.com/element-hq/synapse/releases/tag/v1.138.4
- https://github.com/element-hq/synapse/releases/tag/v1.139.2