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CVE-2026-34516 Moderate

CVE-2026-34516

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.

Exploit probability 0.4%
Published April 1, 2026
Required by Not available
Last source change July 13, 2026

02 / AFFECTED SOFTWARE

Affected packages

PyPI aiohttp

304 explicit affected versions

PyPI aiohttp

304 explicit affected versions

Unknown Unknown

151 explicit affected versions

03 / CONNECTIONS

Connected vulnerabilities

04 / EVIDENCE

Source records

Open Source Vulnerabilities CVE-2026-34516

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.

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Open Source Vulnerabilities GHSA-m5qp-6w8w-w647

### Summary A response with an excessive number of multipart headers may be allowed to use more memory than intended, potentially allowing a DoS vulnerability. ### Impact Multipart headers were not subject to the same size restrictions in place for normal headers, potentially allowing substantially more data to be loaded into memory than intended. However, other restrictions in place limit the impact of this vulnerability. ----- Patch: https://github.com/aio-libs/aiohttp/commit/8a74257b3804c9aac0bf644af93070f68f6c5a6f

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Open Source Vulnerabilities PYSEC-2026-2098

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.

View original source

05 / REFERENCES

Further evidence