CVE-2024-31208
Synapse V2 state resolution weakness allows Denial of Service (DoS)
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.
How to fix CVE-2024-31208
To remediate CVE-2024-31208, upgrade the affected package to a fixed version below.
- —upgrade to 1.103.0-2 or later
- —upgrade to 1.105.1 or later
- —upgrade to 55b0aa847a61774b6a3acdc4b177a20dc019f01a or later
Is CVE-2024-31208 being exploited?
Low — EPSS is 4.2%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 1.103.0-2
- from 0, < 1.105.1
- from 0, < 55b0aa847a61774b6a3acdc4b177a20dc019f01a | from 0, < 1.105.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |