CVE-2026-34519

MEDIUM

AIOHTTP: HTTP response splitting via \r in reason phrase

Title source: cna

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, an attacker who controls the reason parameter when creating a Response may be able to inject extra headers or similar exploits. This issue has been patched in version 3.13.4.

References (3)

[X_Refsource_Confirm] https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mwh4-6h8g-pg8w

[X_Refsource_Misc] https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b

View Writeup ZIP pw:eip

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

Scores

CVSS v3 5.3

EPSS 0.0004

EPSS Percentile 11.7%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-113

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