HTTP response splitting in aiohttp - CVE-2026-50269

Vulnerability identifier: #VU133988

CSH Severity: Medium

CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-50269

CWE-ID: CWE-113

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to inject additional headers or modify the contents of a request.

The vulnerability exists due to improper neutralization of crlf sequences in multipart headers when processing user-controlled header values. A remote attacker can supply crafted input to inject additional headers or modify the contents of a request.

The issue occurs if an application passes user-controlled strings into MultipartWriter.append(headers=...) or Payload.headers.

aiohttp
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise Desktop 15
SUSE Manager Proxy
SUSE Manager Retail Branch Server
SUSE Manager Server
Public Cloud Module
Python 3 Module
openSUSE Leap
python-aiohttp-debugsource
python3-aiohttp-debuginfo
python3-aiohttp
python311-aiohttp
python311-aiohttp-debuginfo

Install security update from vendor's website.

aiohttp - update to 3.14.0
python-aiohttp-debugsource - addressed in versions 3.6.0-150100.3.38.1, 3.9.3-150400.10.43.1
python3-aiohttp-debuginfo - update to 3.6.0-150100.3.38.1
python3-aiohttp - update to 3.6.0-150100.3.38.1
python311-aiohttp - update to 3.9.3-150400.10.43.1
python311-aiohttp-debuginfo - update to 3.9.3-150400.10.43.1

• https://github.com/aio-libs/aiohttp/security/advisories/GHSA-m6qw-4cw2-hm4m
• https://github.com/aio-libs/aiohttp/commit/bf88077ebb14f4c29924b8e8904cba20c55c28b8

• Multiple vulnerabilities in aiohttp
• SUSE update for python-aiohttp
• SUSE update for python-aiohttp