CVE Vulnerability

CVE-2021-29471

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.

5 /10

CVSS v2.0 :

V3 Legend

Vector :

Exploitability : 10 / Impact : 2.9

Attack Vector

Attack Complexity

Privileges Required

User Interaction

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact PARTIAL

Scope

5.3 /10

CVSS v3.0 : MEDIUM

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References
Link Resource
https://github.com/matrix-org/synapse/releases/tag/v1.33.2 Release Notes Third Party Advisory
https://github.com/matrix-org/synapse/security/advisories/GHSA-x345-32rc-8h85 Patch Third Party Advisory
https://github.com/matrix-org/synapse/commit/03318a766cac9f8b053db2214d9c332a977d226c Patch Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/ Mailing List Third Party Advisory
Configurations

Configuration 1

cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
Information

Published : 2021-05-11 03:15

Updated : 2022-04-05 06:06

NVD link : CVE-2021-29471

Mitre link : CVE-2021-29471

Products Affected
No products.
CWE
CWE-331

Insufficient Entropy