AIOHTTP vulnerable to DoS through chunked messages

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2025-69229: 0.40% estimated exploitation activity in the next 30 days; percentile 34.74 (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 Handling of chunked messages can result in excessive blocking CPU usage when receiving a large number of chunks. Impact If an application makes use of the request.read() method in an endpoint, it may be possible for an attacker to cause the server to spend a moderate amount of blocking CPU time (e.g. 1 second) while processing the request. This could potentially lead to DoS as the server would be unable to handle other requests during that time. ----- Patch: https://github.com/aio-libs/aiohttp/commit/dc3170b56904bdf814228fae70a5501a42a6c712 Patch: https://github.com/aio-libs/aiohttp/commit/4ed97a4e46eaf61bd0f05063245f613469700229

Published by the source

5 Jan 2026, 23:13 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:36 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g84x-mcqj-x9qq

2. Revision 2 · amended · 24 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-g84x-mcqj-x9qq

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2025-69229

Advisory: AIOHTTP vulnerable to DoS through chunked messages
IDs: CVE-2025-69229, GHSA-g84x-mcqj-x9qq
Record: https://patchnext.com/advisories/cve-2025-69229 (revision 3, source checked 26 Oct 2026, 13:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: aiohttp 3.13.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI aiohttp: affected <= 3.13.2; fixed in 3.13.3

## 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-g84x-mcqj-x9qq (OSV record GHSA-g84x-mcqj-x9qq lists affected ranges: PyPI aiohttp >=0 <3.13.3 (fixed))
- Verified: https://github.com/advisories/GHSA-g84x-mcqj-x9qq (GitHub-reviewed advisory GHSA-g84x-mcqj-x9qq lists affected ranges: PyPI aiohttp >=0 <=3.13.2)

Commands are suggestions: review each one before running it.