CVE-2026-34520

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.

Scoring

Severity
LOW
CVSS base score
9.1
CVSS vector
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
EPSS probability
0.46%
CWE
CWE-113
Published
2026-04-01
Last modified
2026-04-04

Affected products

Weakness type

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