GitHub Advisoryadvisory · PyPI

GHSA-8q93-326v-3m7g Synapse CPU starvation (Denial of Service)

HIGH Published 2026-05-14 Modified 2026-06-09 Official page ↗
Aliases
CVE-2026-45078
Ecosystem
PyPI
Packages
matrix-synapse
Severity
High
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weaknesses
CWE-400, CWE-770
Reviewed
2026-05-14

Affected packages

• PyPI matrix-synapse: < 1.152.1 → fixed in 1.152.1

Description

Impact 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. Homeservers that trust all their local users are not at risk. Patches Update to Synapse 1.152.1 or later. Workarounds If Synapse is deployed behind a reverse proxy, the reverse proxy could be configured to limit the rate of user requests, preventing or increasing the difficulty of the attack. Identifiers • ELEMENTSEC-2026-1706 For more information If you have any questions or comments about this advisory, please email us at security at element.io.

Related

Alias · CVE (1)

  • CVE-2026-45078 Synapse is an open source Matrix homeserver implementation. vulnerability

Weakness · CWE (2)

  • CWE-400 Uncontrolled Resource Consumption weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling weakness

References