CVE-2026-45078: Element Synapse

Medium severity, CVSS 5.5. EPSS: 0.1% chance of exploitation in the next 30 days.

Synapse is an open source Matrix homeserver implementation. Prior to 1.152.1, local authenticated users can cause Synapse to starve other requests of CPU and lead to other requests failing, causing other users to be denied service. 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.