aiohttp has a memory leak when middleware is enabled when requesting a resource with a non-allowed method

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.9 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2024-52303: 0.59% estimated exploitation activity in the next 30 days; percentile 48.32 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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

Published by the source

18 Nov 2024, 21:02 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:27 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-27mf-ghqm-j3j8

2. Revision 2 · amended · 25 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-27mf-ghqm-j3j8

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# Patch Next advisory brief: CVE-2024-52303

Advisory: aiohttp has a memory leak when middleware is enabled when requesting a resource with a non-allowed method
IDs: CVE-2024-52303, GHSA-27mf-ghqm-j3j8
Record: https://patchnext.com/advisories/cve-2024-52303 (revision 3, source checked 26 Oct 2026, 13:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: aiohttp 3.10.11. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI aiohttp: affected >= 3.10.6, < 3.10.11; fixed in 3.10.11

## Suggested inspection (read-only)
- `python -m pip show aiohttp`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on aiohttp.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-27mf-ghqm-j3j8 (OSV record GHSA-27mf-ghqm-j3j8 lists affected ranges: PyPI aiohttp >=3.10.6 <3.10.11 (fixed))
- Verified: https://github.com/advisories/GHSA-27mf-ghqm-j3j8 (GitHub-reviewed advisory GHSA-27mf-ghqm-j3j8 lists affected ranges: PyPI aiohttp >=3.10.6 <3.10.11)

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