| Package | Affected versions | Patched versions |
|---|---|---|
| matrix-synapse | < 1.33.2 | 1.33.2 |
| synapse | < 1.33.2 | 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 by https://github.com/matrix-org/synapse/commit/03318a766cac9f8b053db2214d9c332a977d226c.
A potential workaround might be to prevent users from making custom push rules, by blocking such requests at a reverse-proxy.
If you have any questions or comments about this advisory, email us at [email protected].
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