aiohttp allows request smuggling due to incorrect parsing of chunk extensions

Exploitation

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

CVSS 4.0

6.3 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X · score source

EPSS

• CVE-2024-52304: 0.56% estimated exploitation activity in the next 30 days; percentile 46.88 (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 The Python parser parses newlines in chunk extensions incorrectly which can lead to request smuggling vulnerabilities under certain conditions. Impact If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTPNOEXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections. ----- Patch: https://github.com/aio-libs/aiohttp/commit/259edc369075de63e6f3a4eaade058c62af0df71

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, 13:35 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-8495-4g3g-x7pr

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-8495-4g3g-x7pr

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# Patch Next advisory brief: CVE-2024-52304

Advisory: aiohttp allows request smuggling due to incorrect parsing of chunk extensions
IDs: CVE-2024-52304, GHSA-8495-4g3g-x7pr
Record: https://patchnext.com/advisories/cve-2024-52304 (revision 3, source checked 26 Oct 2026, 13:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
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 <= 3.10.10; 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-8495-4g3g-x7pr (OSV record GHSA-8495-4g3g-x7pr lists affected ranges: PyPI aiohttp >=0 <3.10.11 (fixed))
- Verified: https://github.com/advisories/GHSA-8495-4g3g-x7pr (GitHub-reviewed advisory GHSA-8495-4g3g-x7pr lists affected ranges: PyPI aiohttp >=0 <=3.10.10)

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