CVE-2024-31208

Medium

Description

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.

SeverityMedium
CVSS6.5
Exploit probability—
ProductMatrix Synapse
PublishedApr 23, 2024
First seenApr 23, 2024

How to fix

Update
  • matrix synapse1.105.1 or later
  • matrix-synapse1.105.1 or later

Affected products

ProductAffected versionsFixed in
matrix synapsev < 1.105.11.105.1
fedoraproject fedora38, 39, 40—
matrix-synapsePyPIv < 1.105.11.105.1

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