CVE-2026-128126

UNKNOWN 0.0

AIOHTTP: Too many URL-encoded form fields block the event loop

CVSS Score

0.0

EPSS Score

0.0%

EPSS Percentile

0th

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, Request.post() does not limit the number of fields in a URL-encoded form body, and inserting many repeated keys into MultiDict takes quadratic time on the event loop. A remote attacker can send a form POST within client_max_size to a handler that calls Request.post() and block the event loop. This issue is fixed in version 3.14.4.

CWE	CWE-407
Vendor	aio-libs
Product	aiohttp
Published	Nov 13, 2026

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Affected Versions

aio-libs / aiohttp

< 3.14.4

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/aio-libs/aiohttp/security/advisories/GHSA-xgw8-8ccx-rmqh github.com: https://github.com/aio-libs/aiohttp/pull/13738 github.com: https://github.com/aio-libs/aiohttp/pull/13741 github.com: https://github.com/aio-libs/aiohttp/commit/615fec3d4f088f30d2ee72cad760152e92aa1c53 github.com: https://github.com/aio-libs/aiohttp/commit/8b0100572936df28977b9de8a6cc7e464c0b521e github.com: https://github.com/aio-libs/aiohttp/releases/tag/v3.14.4