CVE-2023-43796: Fedoraproject Fedora

Medium severity, CVSS 5.3. EPSS: 0.9% chance of exploitation in the next 30 days.

Synapse is an open-source Matrix homeserver Prior to versions 1.95.1 and 1.96.0rc1, cached device information of remote users can be queried from Synapse. This can be used to enumerate the remote users known to a homeserver. System administrators are encouraged to upgrade to Synapse 1.95.1 or 1.96.0rc1 to receive a patch. As a workaround, the `federation_domain_whitelist` can be used to limit federation traffic with a homeserver.

Affected products

• Fedoraproject Fedora: version 38 only; version 39 only
• Matrix Synapse: before 1.95.1 (fixed in 1.95.1)

Published 2023-10-31. Last modified 2026-06-17.