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CVE-2026-34519

AIOHTTP: HTTP response splitting via \r in reason phrase

Published: Apr 1, 2026Updated: Apr 16, 2026 Sources: CVE List NVDCWE-113
NVD MITRE
5.3CVSSMEDIUM
EPSS Score
0.3%
Top 79.4%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

Description

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 Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-113

Affected Products

aiohttpaiohttp
Library
OSS Libraries / web-framework
aiohttpaio-libs
Library
OSS Libraries / web-framework
aiohttposs-projectOSS Libraries
aio-libsoss-projectOSS Librariesaka aiohttp, aiosmtpd, aiohttp session

Exploitability

Official Patch Available

References

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

Timeline

Published
Apr 1, 2026
Last Updated
Apr 16, 2026

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