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CVE-2026-34525

AIOHTTP: Duplicate Host header accepted

Published: Apr 1, 2026Updated: Apr 16, 2026 Sources: CVE List NVDCWE-20
5.3MEDIUM
NVD MITRE
EPSS Score
0.3%
Top 79.0%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, multiple Host headers were allowed in aiohttp. This issue has been patched in version 3.13.4.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:LA:N
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:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-20CWE-444

Affected Products

aiohttp
oss-project
aiohttpLibrary
OSS Libraries / web-framework
aio-libs
oss-projectaka aiohttp session, aiosmtpd, aiohttp
aiohttpLibrary
OSS Libraries / web-framework

Exploitability

Official Patch Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques
Collection
Initial Access
View detailed technique mapping

References

https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000
github.com
https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349
github.com
https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4
github.com
and 1 more references View all →

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