CVE-2026-45076: Element Synapse

Low severity, CVSS 2.7. EPSS: 0.4% chance of exploitation in the next 30 days.

Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, in federated rooms, malicious homeservers can craft room events in such a way that prevents Synapse from providing full history to paginating clients. Clients could therefore fail to display room history. This vulnerability is fixed in 1.152.1.

Affected products

• Element Synapse: before 1.152.1 (fixed in 1.152.1)

Published 2026-05-28. Last modified 2026-06-17.