CVE-2026-111748: AIOHTTP: Absolute-form request targets can spoof Request.scheme

Severity: medium (CVSS 6.3 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-19 · updated 2026-10-19
Weakness: CWE-807

Description

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.4, an attacker can send an absolute-form request that causes Request.scheme to use attacker-controlled request-target scheme data instead of the connection protocol. Applications that use Request.scheme for security decisions can consequently be tricked into treating an unencrypted connection as encrypted or an encrypted connection as unencrypted. This issue is fixed in version 3.14.4.

Affected products

Pypi Aiohttp: before 3.14.4; 0.1, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 0.12.0 (+304) — fixed in 3.14.4
aio-libs aiohttp: before 3.14.4

How to fix

Upgrade to a fixed version: Pypi Aiohttp 3.14.4. Check the vendor advisory for mitigations.

References

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