Description
Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. A malicious user on a Synapse homeserver X with permission to create certain state events can disable outbound federation from X to an arbitrary homeserver Y. Synapse instances with federation disabled are not affected. In versions of Synapse up to and including 1.73, Synapse did not limit the size of `invite_room_state`, meaning that it was possible to create an arbitrarily large invite event. Synapse 1.74 refuses to create oversized `invite_room_state` fields. Server operators should upgrade to Synapse 1.74 or newer urgently.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:LWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| matrix-org | synapse | < 1.74.0 |
References
- https://github.com/matrix-org/synapse/issues/14492Exploit, Issue Tracking
- https://github.com/matrix-org/synapse/pull/14642Patch
- https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvrMitigation, Vendor Advisory
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/
- https://github.com/matrix-org/synapse/issues/14492Exploit, Issue Tracking
- https://github.com/matrix-org/synapse/pull/14642Patch
- https://github.com/matrix-org/synapse/security/advisories/GHSA-f3wc-3vxv-xmvrMitigation, Vendor Advisory
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UJIJRP5ZH6B3KGFLHCAKR2IX2Y4Z25QD/
Timeline
- Published
- May 26, 2023
- Last modified
- Jun 17, 2026
- NVD status
- Modified