CVE-2026-34517

AIOHTTP: Late size enforcement for non-file multipart fields causes memory DoS

State: Published
Severity: 2.7 Low
Published: Apr 1, 2026
Updated: Jun 23, 2026
Reserved: Mar 30, 2026

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, for some multipart form fields, aiohttp read the entire field into memory before checking client_max_size. This issue has been patched in version 3.13.4.

Scores

CVSS	Score	Vector	Source
4.0	2.7 Low	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/E:U	GitHub_M

Weaknesses

CWE-770 Allocation of Resources Without Limits or Throttling

Affected Products

Product	Versions
aiohttpaio-libs	< 3.13.4Affected

References

https://github.com/aio-libs/aiohttp/security/advisories/GHSA-3wq7-rqq7-wx6j
https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145
https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4

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