GHSA-x345-32rc-8h85 Denial of service attack via push rule patterns in matrix-synapse

• PyPI matrix-synapse: < 1.33.2 → fixed in 1.33.2

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].