GHSA-27mf-ghqm-j3j8
HIGHaiohttp has a memory leak when middleware is enabled when requesting a resource with a non-allowed method
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
aiohttpReal-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
Summary
A memory leak can occur when a request produces a MatchInfoError. This was caused by adding an entry to a cache on each request, due to the building of each MatchInfoError producing a unique cache entry.
Impact
If the user is making use of any middlewares with aiohttp.web then it is advisable to upgrade immediately.
An attacker may be able to exhaust the memory resources of a server by sending a substantial number (100,000s to millions) of such requests.
Patch: https://github.com/aio-libs/aiohttp/commit/bc15db61615079d1b6327ba42c682f758fa96936
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | aiohttp | ≥ 3.10.6&&< 3.10.11 | 3.10.11 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for aiohttp. 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 aiohttp to 3.10.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-27mf-ghqm-j3j8 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-27mf-ghqm-j3j8 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-27mf-ghqm-j3j8. 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-27mf-ghqm-j3j8 in your dependencies?
O3 detects GHSA-27mf-ghqm-j3j8 across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.