Ecosyste.ms: Advisories

Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLXgzNDUtMzJyYy04aDg1

Denial of service attack via push rule patterns in matrix-synapse

Impact

"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.

Patches

The issue is patched by https://github.com/matrix-org/synapse/commit/03318a766cac9f8b053db2214d9c332a977d226c.

Workarounds

A potential workaround might be to prevent users from making custom push rules, by blocking such requests at a reverse-proxy.

For more information

If you have any questions or comments about this advisory, email us at [email protected].

Permalink: https://github.com/advisories/GHSA-x345-32rc-8h85
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLXgzNDUtMzJyYy04aDg1
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Low
Classification: General
Published: over 2 years ago
Updated: 10 months ago

CVSS Score: 3.7
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Identifiers: GHSA-x345-32rc-8h85, CVE-2021-29471
References:

• https://github.com/matrix-org/synapse/security/advisories/GHSA-x345-32rc-8h85
• https://github.com/matrix-org/synapse/commit/03318a766cac9f8b053db2214d9c332a977d226c
• https://nvd.nist.gov/vuln/detail/CVE-2021-29471
• https://github.com/matrix-org/synapse/releases/tag/v1.33.2
• https://lists.fedoraproject.org/archives/list/[email protected]/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/
• https://github.com/advisories/GHSA-x345-32rc-8h85

Affected Packages