CVE-2024-31208: Fedoraproject Fedora

Medium severity, CVSS 6.5. EPSS: 1.5% chance of exploitation in the next 30 days.

Synapse is an open-source Matrix homeserver. A remote Matrix user with malicious intent, sharing a room with Synapse instances before 1.105.1, can dispatch specially crafted events to exploit a weakness in the V2 state resolution algorithm. This can induce high CPU consumption and accumulate excessive data in the database of such instances, resulting in a denial of service. Servers in private federations, or those that do not federate, are not affected. Server administrators should upgrade to 1.105.1 or later. Some workarounds are available. One can ban the malicious users or ACL block servers from the rooms and/or leave the room and purge the room using the admin API.

Affected products

• Fedoraproject Fedora: version 38 only; version 39 only; version 40 only
• Matrix Synapse: before 1.105.1 (fixed in 1.105.1)

Published 2024-04-23. Last modified 2026-06-17.