Impact
A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a /send_join, /send_leave, /invite or /exchange_third_party_invite request.
This can lead to a denial of service in which future events will not be correctly sent to other servers over federation.
This affects any server which accepts federation requests from untrusted servers.
Patches
Issue is resolved by #8776.
Workarounds
Homeserver administrators could limit access to the federation API to trusted servers (for example via federation_domain_whitelist).
Impact
A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a
/send_join,/send_leave,/inviteor/exchange_third_party_inviterequest.This can lead to a denial of service in which future events will not be correctly sent to other servers over federation.
This affects any server which accepts federation requests from untrusted servers.
Patches
Issue is resolved by #8776.
Workarounds
Homeserver administrators could limit access to the federation API to trusted servers (for example via
federation_domain_whitelist).