CVE-2026-34519

EUVD-2026-18044
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.
HTTP Request/Response Splitting
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
UNKNOWN
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Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Common Weakness Enumeration
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