CVE-2025-61672mediumCWE-1287

CVE-2025-61672: medium-severity vulnerability in element-hq synapse

Synapse: Invalid device keys degrade federation functionality

Published · Updated

Follow this CVE+ Monitor synapse+ Monitor matrix-synapse

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 5.3epss 0.5%
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:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
Affected products
element-hq · synapse
Related CVEs — element-hq synapse

In the same product, most dangerous first.

CVE-2024-31208MEDIUMSynapse's V2 state resolution weakness allows DoS from remote room membersEPSS 1.5%CVE-2025-30355HIGHSynapse vulnerable to federation denial of service via malformed eventsEPSS 1.2%CVE-2024-52805HIGHSynapse allows unsupported content types to lead to memory exhaustionEPSS 0.7%CVE-2024-53863HIGHSynapse can be forced to thumbnail unexpected file formats, invoking external, potentially untrustworthy decodersEPSS 0.6%CVE-2024-37302HIGHSynapse denial of service through media disk space consumptionEPSS 0.6%CVE-2024-52815HIGHSynapse allows a a malformed invite to break the invitee's `/sync`EPSS 0.6%