GHSA-jhjh-776m-4765 Denial of service due to incorrect application of event authorization rules

• PyPI matrix-synapse: < 1.62.0rc1 → fixed in 1.62.0rc1

Impact The Matrix specification specifies a list of event authorization rules which must be checked when determining if an event should be accepted into a room. In versions of Synapse up to and including v1.61, some of these rules are not correctly applied. An attacker could craft events which would be accepted by Synapse but not a spec-conformant server, potentially causing divergence in the room state between servers. Patches Administrators of homeservers with federation enabled are advised to upgrade to v1.62.0 or higher. Workarounds • Federation can be disabled by setting `federation_domain_whitelist` to an empty list (`[]`). References • https://github.com/matrix-org/synapse/pull/13087 • https://github.com/matrix-org/synapse/pull/13088 For more information If you have any questions or comments about this advisory, e-mail us at [email protected].