5
CVSSv2

CVE-2021-29471

Published: 11/05/2021 Updated: 07/11/2023
CVSS v2 Base Score: 5 | Impact Score: 2.9 | Exploitability Score: 10
CVSS v3 Base Score: 5.3 | Impact Score: 1.4 | Exploitability Score: 3.9
VMScore: 445
Vector: AV:N/AC:L/Au:N/C:N/I:N/A:P

Vulnerability Summary

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.

Vulnerability Trend

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matrix synapse

fedoraproject fedora 34

Vendor Advisories

In Synapse before version 1332 "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 pat ...