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[email protected]CVE-2021-29471

HistoryMay 11, 2021 - 3:15 p.m.

CVE-2021-29471

2021-05-1115:15:08

CWE-400

CWE-331

[email protected]

web.nvd.nist.gov

synapse

matrix

homeserver

denial-of-service

push rules

cybersecurity

vulnerability

cve-2021-29471

5 Medium

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

PARTIAL

AV:N/AC:L/Au:N/C:N/I:N/A:P

5.3 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

LOW

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

5.3 Medium

AI Score

Confidence

High

0.002 Low

EPSS

Percentile

51.9%

JSON

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

Vulners

NVD

Node

matrix-orgsynapseRange<1.33.2

CPENameOperatorVersion
matrix:synapsematrix synapselt1.33.2

CPE	Name	Operator	Version
matrix:synapse	matrix synapse	lt	1.33.2

CNA Affected

[
  {
    "product": "synapse",
    "vendor": "matrix-org",
    "versions": [
      {
        "status": "affected",
        "version": "< 1.33.2"
      }
    ]
  }
]