CVE-2026-34516 — Allocation of Resources Without Limits or Throttling in Aiohttp

CWE-770 — Allocation of Resources Without Limits or Throttling8 documents7 sources
Severity
6.6MEDIUMNVD
EPSS
0.1%
top 83.69%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Aio-libs AiohttpAiohttp
Timeline
PublishedApr 1

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

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Affected Packages2 packages

▶PyPIaiohttp/aiohttp< 3.13.4
▶CVEListV5aio-libs/aiohttp< 3.13.4

🔴Vulnerability Details

4
OSV
CVE-2026-34516: AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python↗2026-04-01
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CVEList
AIOHTTP: Multipart Header Size Bypass↗2026-04-01
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OSV
AIOHTTP has a Multipart Header Size Bypass↗2026-04-01
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GHSA
AIOHTTP has a Multipart Header Size Bypass↗2026-04-01
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📋Vendor Advisories

2
Red Hat
aiohttp: AIOHTTP: Denial of Service via excessive multipart headers↗2026-04-01
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Debian
CVE-2026-34516: python-aiohttp - AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. ...↗2026
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🕵️Threat Intelligence

1
Wiz
CVE-2026-34516 Impact, Exploitability, and Mitigation Steps | Wiz↗
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CVE-2026-34516 — Aio-libs Aiohttp vulnerability | cvebase