CVE-2026-34520

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.

References

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