CVE-2023-45129: Fedoraproject Fedora

Medium severity, CVSS 4.9. EPSS: 1.2% chance of exploitation in the next 30 days.

Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Prior to version 1.94.0, 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. Server administrators are advised to upgrade to Synapse 1.94.0 or later. As a workaround, rooms with malicious server ACL events can be purged and blocked using the admin API.

Affected products

• Fedoraproject Fedora: version 37 only; version 38 only
• Matrix Synapse: before 1.94.0 (fixed in 1.94.0)

Published 2023-10-10. Last modified 2026-06-17.