CVE-2025-69225: AIOHTTP Regex Mismatch Allows Unicode in ASCII-Only Protocol Fields

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-01-06 · updated 2026-10-11
Weakness: CWE-444

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Versions 3.13.2 and below contain parser logic which allows non-ASCII decimals to be present in the Range header. There is no known impact, but there is the possibility that there's a method to exploit a request smuggling vulnerability. This issue is fixed in version 3.13.3.

Affected products

aio-libs aiohttp: before 3.13.3 — fixed in 3.13.3
Pypi Aiohttp: before 3.13.3; 0.1, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 0.12.0 (+297) — fixed in 3.13.3

How to fix

Upgrade to a fixed version: aio-libs aiohttp 3.13.3; Pypi Aiohttp 3.13.3. Check the vendor advisory for mitigations.

References

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