CVEvulnerability

CVE-2021-29471

5.3 MEDIUM Published 2021-05-11 Modified 2026-06-17 Official page ↗
Status
Modified
Published
2021-05-11
Last modified
2026-06-17
Assigner
[email protected]
CVSS 3.1 ([email protected])
3.7 LOW — CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS 3.1 ([email protected])
5.3 MEDIUM — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS 2.0 ([email protected])
5.0 MEDIUM — AV:N/AC:L/Au:N/C:N/I:N/A:P
Weaknesses
CWE-331, CWE-400

Description

Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.33.2 "Push rules" can specify conditions under which they will match, including `event_match`, which matches event content against a pattern including wildcards. Certain patterns can cause very poor performance in the matching engine, leading to a denial-of-service when processing moderate length events. The issue is patched in version 1.33.2. A potential workaround might be to prevent users from making custom push rules, by blocking such requests at a reverse-proxy.

Affected configurations

• matrix synapse (< 1.33.2) • fedoraproject fedora 34

Related

Weakness · CWE (2)

  • CWE-331 Insufficient Entropy weakness
  • CWE-400 Uncontrolled Resource Consumption weakness

References