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CVE-2026-34516

AIOHTTP: Multipart Header Size Bypass

Published: Apr 1, 2026Updated: Apr 15, 2026 Sources: CVE List NVDCWE-770
NVD MITRE
7.5CVSSHIGH
EPSS Score
0.4%
Top 65.0%
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, a response with an excessive number of multipart headers may be allowed to use more memory than intended, potentially allowing a DoS vulnerability. This issue has been patched in version 3.13.4.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
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:NIntegrity
None
A:HAvailability
High
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Weaknesses

CWE-770

Affected Products

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

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

https://github.com/aio-libs/aiohttp/security/advisories/GHSA-m5qp-6w8w-w647
github.com
https://github.com/aio-libs/aiohttp/commit/8a74257b3804c9aac0bf644af93070f68f6c5a6f
github.com
https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4
github.com

Timeline

Published
Apr 1, 2026
Last Updated
Apr 15, 2026

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