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aiohttp CVE-2026-69243

| EUVDEUVD-2026-52436 MEDIUM
HTTP Request/Response Smuggling (CWE-444)
2026-08-03 GitHub_M GHSA-mfx4-hv73-q22v
Python Information Disclosure Request Smuggling Aiohttp Red Hat
6.3
CVSS 4.0 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
6.3 MEDIUM
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
3.7 LOW

Network vector, no auth required, but AC:H reflects the specific crafted-body WebSocket upgrade edge case; integrity-only, no scope change per provided 4.0 SC/SI/SA:N.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
SUSE
5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Red Hat
7.0 MEDIUM
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

3
Patch available
Aug 03, 2026 - 22:17 EUVD
Source Code Evidence Fetched
Aug 03, 2026 - 21:37 vuln.today
Analysis Generated
Aug 03, 2026 - 21:37 vuln.today

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 4 pypi packages depend on aiohttp (4 direct, 0 indirect)

Ecosystem-wide dependent count for version 3.14.2.

DescriptionCVE.org

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the HTTP parsers were vulnerable to a request smuggling attack relating to WebSocket upgrades. If using the server-side component, an attacker may be able to execute a request smuggling vulnerability using an edge case in the WebSocket upgrade procedure. A WebSocket upgrade request with a body could cause the parser to switch protocols before the complete request body was received, leaving trailing bytes to be handled as upgraded-protocol or pipelined data rather than normal HTTP body data. This issue is fixed in version 3.14.2.

AnalysisAI

HTTP request smuggling in aiohttp's server-side parser allows unauthenticated remote attackers to inject and misdirect HTTP traffic by exploiting a protocol-switch race in the WebSocket upgrade path. Versions 3.14.1 and earlier prematurely mark the connection as upgraded before the full request body is consumed, causing trailing bytes - potentially an attacker-controlled HTTP request - to be interpreted as WebSocket or pipelined data by the server or any upstream proxy. No public exploit code exists and the vulnerability is not listed in CISA KEV, but CVSS 4.0 AC:H reflects the edge-case nature of the trigger condition.

Technical ContextAI

aiohttp (CPE: cpe:2.3:a:aio-libs:aiohttp:*:*:*:*:*:*:*:*) is a widely used asynchronous HTTP client/server framework for Python's asyncio, implemented in both Python (http_parser.py) and Cython (_http_parser.pyx). The root cause is CWE-444 (Inconsistent Interpretation of HTTP Requests). RFC 9110 §7.8 requires that a protocol upgrade take effect only after the complete HTTP request - including body - has been received. The vulnerable parser set the _upgraded = True flag upon seeing Connection: Upgrade and a supported Upgrade header during headers-complete processing, before any body bytes were consumed. A WebSocket upgrade request carrying a Content-Length or chunked body thus caused the parser to transition to the upgraded protocol mid-stream, leaving unread body bytes to spill into the upgraded-protocol or pipelined-request processing path. The fix introduces a _pending_upgrade boolean in both the Cython and Python parser implementations, deferring the actual _upgraded = True assignment until the payload reader confirms the body is fully consumed.

RemediationAI

Upgrade to aiohttp 3.14.2 or later via pip (pip install 'aiohttp>=3.14.2'); this is the vendor-confirmed patch. The fix is implemented in commit 6ae358f0983c3f4d6f67692b2f8e65dc8e091c98 (PR #13017) and defers the WebSocket protocol switch until the full request body is consumed. No workaround is available that preserves WebSocket upgrade functionality - disabling WebSocket support entirely would eliminate the attack surface if WebSockets are not operationally required, though this would be a significant functional trade-off. In reverse-proxy deployments (e.g., nginx in front of aiohttp), configuring the proxy to strip or reject WebSocket upgrade requests with a non-empty body before they reach the aiohttp backend can serve as a compensating control until patching is possible. References: vendor advisory at https://github.com/aio-libs/aiohttp/security/advisories/GHSA-mfx4-hv73-q22v; patch PR at https://github.com/aio-libs/aiohttp/pull/13017.

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Module for Public Cloud 15 SP7 Affected
SUSE Linux Enterprise Module for Python 3 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected

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CVE-2026-69243 vulnerability details – vuln.today
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