Element-hq Synapse vulnerabilities

🔔 Create alert RSS Version checker

Published CVEs affecting Element-hq Synapse: 3 record(s), with affected versions and fixes.

CVE-2026-45078 Medium · 5.5 CWE-770 May 28, 2026

Synapse CPU starvation (Denial of Service)

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.

CVE-2026-45076 Low · 2.7 CWE-20 May 28, 2026

Synapse pagination denial of service

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.

CVE-2025-61672 Medium · 5.3 CWE-1287 Oct 8, 2025

Synapse: Invalid device keys degrade federation functionality

Synapse is an open source Matrix homeserver implementation. Lack of validation for device keys in Synapse before 1.138.3 and in Synapse 1.139.0 allow an attacker registered on the victim homeserver to degrade federation functionality, unpredictably breaking outbound federation to other homeservers. The issue is patched in Synapse 1.138.3, 1.138.4, 1.139.1, and 1.139.2. Note that even though 1.138.3 and 1.139.1 fix the vulnerability, they inadvertently introduced an unrelated regression. For this reason, the maintainers of Synapse recommend skipping these releases and upgrading straight to 1.138.4 and 1.139.2.