PYSEC-2026-2102

At a glance

Published: 2026-04-01 21:17 UTC
Updated: 2026-07-13 07:15 UTC
CVE: CVE-2026-34520
Aliases: GHSA-63hf-3vf5-4wqf
CVSS_V4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, the C parser (the default for most installs) accepted null bytes and control characters in response headers. This issue has been patched in version 3.13.4.

Affected packages

Package	Versions
PyPI · aiohttp	introduced 0, fixed 3.13.4

References

https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4 ADVISORY
https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4 FIX
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hf-3vf5-4wqf FIX

Sources

Source	Licence
OSV.dev	CC-BY 4.0 — PyPA Advisory Database