medium6.5

CVE-2024-31208

Synapse V2 state resolution weakness allows Denial of Service (DoS)

Impact

### Impact 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 how the auth chain cover index is calculated. 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. ### Patches Server administrators should upgrade to 1.105.1 or later. ### Workarounds 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 ### For more information If you have any questions or comments about this advisory, please email us at [security AT element.io](mailto:security@element.io).

Affected packages

Ecosystem	Package	Affected	Fixed in
pip	`matrix-synapse`	< 1.105.1	1.105.1

Affected products

Vendor	Product	Affected versions
Matrix	Synapse	before 1.105.1
Fedoraproject	Fedora	Versions 38, 39, 40

Weakness classification

CWE-770

Impact

Affected packages

Affected products

Weakness classification

References