Impact
A malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service.
Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected.
Patches
Server administrators are advised to upgrade to Synapse 1.94.0 or later.
Workarounds
Rooms with malicious server ACL events can be purged and blocked using the admin API.
References
#16360
Impact
A malicious server ACL event can impact performance temporarily or permanently leading to a persistent denial of service.
Homeservers running on a closed federation (which presumably do not need to use server ACLs) are not affected.
Patches
Server administrators are advised to upgrade to Synapse 1.94.0 or later.
Workarounds
Rooms with malicious server ACL events can be purged and blocked using the admin API.
References
#16360