CVE-2026-34519

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, an attacker who controls the reason parameter when creating a Response may be able to inject extra headers or similar exploits. This issue has been patched in version 3.13.4.

CVSS 4.0

2.7CVSS: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

CVSS 3.1

5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS

0.3% chance of exploitation in the next 30 days; higher than 21% of CVEs (scores of 2026-10-26)

CWE

CWE-113

Published

2026-04-01

Modified

2026-10-26

Record from

the NVD, synced 2026-10-26

Affected

• aiohttp:aiohttp

Packages (OSV)

References

• https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b
• https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4
• https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mwh4-6h8g-pg8w

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