CVE-2026-34520 — AIOHTTP: C parser (llhttp) accepts null bytes and control characters in response header values - header injection / s…

CVE-2026-34520

AIOHTTP: C parser (llhttp) accepts null bytes and control characters in response header values - header injection / security bypass PUBLISHED

Description (CNA)

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 (CNA)

Vendor / product	Versions
aio-libs / aiohttp	affected < 3.13.4

CWE

CWE-113

References

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

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.