First published: Tue Apr 23 2024(Updated: )
### 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).
Credit: security-advisories@github.com security-advisories@github.com
Affected Software | Affected Version | How to fix |
---|---|---|
pip/matrix-synapse | <1.105.1 | 1.105.1 |
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