Synapse Denial of service due to incorrect application of event authorization rules during state resolution
If Synapse and a malicious homeserver are both joined to the same room, the malicious homeserver can trick Synapse into accepting previously rejected events into its view of the current state of that room. This can be exploited in a way that causes all further messages and state changes sent in that room from the vulnerable homeserver to be rejected.
Synapse homeservers are affected by this issue if and only if they are joined to rooms which members of untrusted homeservers are joined or invited to.
Administrators of homeservers with federation enabled are advised to upgrade to 1.68.0 or higher.
federation_domain_allow listto an empty list (
m.federate in the
If you have any questions or comments about this advisory, e-mail us at firstname.lastname@example.org.
All versions starting from 1.62.0 before 1.68.0
Upgrade to version 1.68.0 or above.