Name: CVE-2025-61672: Improper Validation of Specified Type of Input
Creator: Rapid7
Published: 2025-10-08T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2025-61672, CWE-1287, CVSS 5.3, EPSS 0.00058

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.

CVSS Details

CVSS 4.0 Base Score: 5.3 (MEDIUM)
CVSS 4.0 Vector: (CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Alpine Linux	—	Upgrade synapse	Oct 9, 2025	Oct 8, 2025

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CVSS Details

Covered by Rapid7

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