CVE-2026-34519: AIOHTTP: HTTP response splitting via \r in reason phrase
Published Apr 1, 2026
·Updated
### Summary An attacker who controls the `reason` parameter when creating a `Response` may be able to inject extra headers or similar exploits. ### Impact In the unlikely situation that an application allows untrusted data to be used in the response's `reason` parameter, then an attacker could manipulate the response to send something different from what the developer intended. ----- Patch: https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b
Affected Software
2 affected componentsFixes available
pip/aiohttp<=3.13.3
3.13.4
aiohttp aiohttp<3.13.4
Remediation
Event History
Apr 1, 2026
CVE Published
via MITRE·08:26 PM
Data Sourced
via MITRE·08:26 PM
DescriptionWeakness
Data Sourced
via NVD·09:17 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·09:17 PM
RemedyAffected Software
Advisory Published
via GitHub·09:48 PM
Data Sourced
via GitHub·09:48 PM
DescriptionWeaknessAffected Software