GHSA-x345-32rc-8h85 is a low-severity (CVSS 3.7) Uncontrolled Resource Consumption vulnerability in matrix-synapse. O3 Security confirms whether GHSA-x345-32rc-8h85 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Denial of service attack via push rule patterns in matrix-synapse
Real-World Exposure
matrix-synapseReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
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].
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | matrix-synapse | all versions | 1.33.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for matrix-synapse. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update matrix-synapse to 1.33.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-x345-32rc-8h85 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-x345-32rc-8h85 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-x345-32rc-8h85. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-x345-32rc-8h85 in your dependencies?
O3 detects GHSA-x345-32rc-8h85 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.