CVE-2026-34520

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, the C parser (the default for most installs) accepted null bytes and control characters in response headers. This issue has been patched in version 3.13.4.

CVSS v3 9.1 CRITICAL

9.1^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4	Patch
https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4	Release Notes
https://github.com/aio-libs/aiohttp/security/advisories/GHSA-63hf-3vf5-4wqf	Patch Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:aiohttp:aiohttp:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-04-01 21:17

Updated : 2026-06-17 10:39

NVD link : CVE-2026-34520

Mitre link : CVE-2026-34520

CVE.ORG link : CVE-2026-34520

JSON object : View

Products Affected

aiohttp

aiohttp

CWE

CWE-113

Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

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