What’s Vulnerable › Vulnerabilities

CVE-2025-69229: AIOHTTP vulnerable to DoS through chunked messages

• Severity: medium (CVSS 5.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-01-06 · updated 2026-10-11
• Weakness: CWE-770

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. In versions 3.13.2 and below, handling of chunked messages can result in excessive blocking CPU usage when receiving a large number of chunks. 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. This issue is fixed in version 3.13.3.

Affected products

• aio-libs aiohttp: before 3.13.3 — fixed in 3.13.3
• Pypi Aiohttp: before 3.13.3; 0.1, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 0.12.0 (+297) — fixed in 3.13.3

How to fix

Upgrade to a fixed version: aio-libs aiohttp 3.13.3; Pypi Aiohttp 3.13.3. Check the vendor advisory for mitigations.

References

• https://github.com/aio-libs/aiohttp/commit/4ed97a4e46eaf61bd0f05063245f613469700229
• https://github.com/aio-libs/aiohttp/commit/dc3170b56904bdf814228fae70a5501a42a6c712
• https://github.com/aio-libs/aiohttp/security/advisories/GHSA-g84x-mcqj-x9qq

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