CVE-2026-34517: AIOHTTP has late size enforcement for non-file multipart fields causes memory DoS

April 1, 2026

For some multipart form fields, aiohttp read the entire field into memory before checking client_max_size.

References

github.com/advisories/GHSA-3wq7-rqq7-wx6j
github.com/aio-libs/aiohttp
github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145
github.com/aio-libs/aiohttp/releases/tag/v3.13.4
github.com/aio-libs/aiohttp/security/advisories/GHSA-3wq7-rqq7-wx6j
nvd.nist.gov/vuln/detail/CVE-2026-34517

Code Behaviors & Features

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