CVE-2026-50269: Aiohttp

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.0, attacker-controlled input included into multipart/payload headers can be used to modify a request to inject additional headers or similar. In the unlikely situation that an application is passing user-controlled strings into MultipartWriter.append(headers=...) or Payload.headers, then an attacker may be able to modify the request to inject headers or change the contents of the request. This vulnerability is fixed in 3.14.0.

Affected products

• Aiohttp Aiohttp: before 3.14.0 (fixed in 3.14.0)

Published 2026-06-22. Last modified 2026-06-26.