CVE-2026-34516

HIGH

AIOHTTP: Multipart Header Size Bypass

Title source: cna

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, a response with an excessive number of multipart headers may be allowed to use more memory than intended, potentially allowing a DoS vulnerability. This issue has been patched in version 3.13.4.

References (3)

[X_Refsource_Confirm] https://github.com/aio-libs/aiohttp/security/advisories/GHSA-m5qp-6w8w-w647

[X_Refsource_Misc] https://github.com/aio-libs/aiohttp/commit/8a74257b3804c9aac0bf644af93070f68f6c5a6f

View Writeup ZIP pw:eip

[X_Refsource_Misc] https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4

Scores

CVSS v3 7.5

EPSS 0.0005

EPSS Percentile 16.2%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment

Exploitation none

Automatable yes

Technical Impact partial

Details

CWE

CWE-770

Status published

Products (3)

aiohttp/aiohttp < 3.13.4

aio-libs/aiohttp < 3.13.4

pypi/aiohttp 0 - 3.13.4PyPI

Published Apr 01, 2026

Tracked Since Apr 02, 2026