Feed/CVE-2026-34520
CVE-2026-34520LOWCVSS 9.1

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

Published Apr 1, 2026·Updated Jul 15, 2026

NVD Description

### Summary The C parser (the default for most installs) accepted null bytes and control characters in request headers. ### Impact An attacker could send header values that are interpreted differently than expected due to the presence of control characters. For example, `request.url.origin()` may return a different value than the raw Host header, or what a reverse proxy interpreted it as., potentially resulting in some kind of security bypass. ----- Patch: https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4

Affected Packages (1)

aiohttpPYPI
Fixed in = 3.13.3

CVSS Vector

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

References

View on NVD Search GitHub Search Google

Get alerted for CVEs like this

Register your stack and get notified within minutes when a matching CVE drops.

Start monitoring free