CVE-2026-34520lowCWE-113

CVE-2026-34520: low-severity vulnerability in aio-libs aiohttp

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

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8Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 2.7epss 0.5%
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.
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
Affected products
aio-libs · aiohttp
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