CVE-2026-34516: AIOHTTP has a Multipart Header Size Bypass

April 1, 2026 (updated April 6, 2026)

A response with an excessive number of multipart headers may be allowed to use more memory than intended, potentially allowing a DoS vulnerability.

References

github.com/advisories/GHSA-m5qp-6w8w-w647
github.com/aio-libs/aiohttp
github.com/aio-libs/aiohttp/commit/8a74257b3804c9aac0bf644af93070f68f6c5a6f
github.com/aio-libs/aiohttp/releases/tag/v3.13.4
github.com/aio-libs/aiohttp/security/advisories/GHSA-m5qp-6w8w-w647
nvd.nist.gov/vuln/detail/CVE-2026-34516

Code Behaviors & Features

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