CVE-2025-61672 - CVE House
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Status published Medium CVE-2025-61672

Synapse: Invalid device keys degrade federation functionality

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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

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Affected Vendor

Affected Software

synapse
Vulnerable Versions:
< 1.138.3, = 1.139.0

Timeline

Official Publish: October 8th, 2025
Last Modified: October 15th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

Weaknesses (CWE)

CWE-1287

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.