[Pkg-matrix-maintainers] Bug#1069763: matrix-synapse: CVE-2024-31208

[Moritz Mühlenhoff]

Source: matrix-synapse
X-Debbugs-CC: team at security.debian.org
Severity: grave
Tags: security

Hi,

The following vulnerability was published for matrix-synapse.

CVE-2024-31208[0]:
| 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.

https://github.com/element-hq/synapse/security/advisories/GHSA-3h7q-rfh9-xm4v
https://github.com/element-hq/synapse/commit/55b0aa847a61774b6a3acdc4b177a20dc019f01a (v1.105.1)


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2024-31208
    https://www.cve.org/CVERecord?id=CVE-2024-31208

Please adjust the affected versions in the BTS as needed.