CVE-2026-34517Low▾ SunlitAIOHTTP has late size enforcement for non-file multipart fields causes memory DoS
▾ Sunlit zone — Low / medium · no exploitation signal
impact 13.8 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 13.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
0.4%
Last analysed / modified upstream
For some multipart form fields, aiohttp read the entire field into memory before checking client_max_size.
If an application uses Request.post() an attacker can send a specially crafted multipart request to force significant temporary memory allocation even when the request is ultimately rejected.
Patch: https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145
aiohttp < 3.13.4Upgrade to a patched release:
aiohttp 3.13.4Connected by shared product, vendor, weakness, or advisory.
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