CVE-2026-34519

AIOHTTP: HTTP response splitting via \r in reason phrase

Published Apr 1, 2026 CVSS 4.0 · 2.7 Low EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4613-1 python-aiohttp security update
Debian DLA Debian DLA DLA-4876-1 python-aiohttp security update
Github GHSA Github GHSA GHSA-mwh4-6h8g-pg8w AIOHTTP has HTTP response splitting via \r in reason phrase
History
Type Values Removed Values Added
First Time appeared Aiohttp
Aiohttp aiohttp
CPEs cpe:2.3:a:aiohttp:aiohttp:*:*:*:*:*:*:*:*
Vendors & Products Aiohttp
Aiohttp aiohttp
Type Values Removed Values Added
First Time appeared Aio-libs
Aio-libs aiohttp
Vendors & Products Aio-libs
Aio-libs aiohttp
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-1286
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}

threat_severity

Moderate

Type Values Removed Values Added
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.
Title AIOHTTP: HTTP response splitting via \r in reason phrase
Weaknesses CWE-113
References
Metrics cvssV4_0

{'score': 2.7, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Apr 2, 2026, 3:40 PM
Reserved
Mar 30, 2026, 4:03 PM
Status
Analyzed
Published
Apr 1, 2026, 9:17 PM
Modified
Oct 26, 2026, 9:10 PM
Severity
Moderate
Public date
Apr 1, 2026, 8:26 PM