HTTP Request Smuggling Affecting aiohttp package, versions [,3.14.4)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-AIOHTTP-21280744
- published20 Oct 2026
- disclosed20 Oct 2026
- creditDenys Pakizh
Introduced: 20 Oct 2026
NewCVE-2026-111750 (opens in a new tab)How to fix?
Upgrade aiohttp to version 3.14.4 or higher.
Overview
Affected versions of this package are vulnerable to HTTP Request Smuggling in the pure-Python HTTP request parser in aiohttp/http_parser.py, where the method variable used to determine whether a request body should be treated as empty is incorrectly sourced from a local parameter rather than self.method. Because self.method is None on the request parser, a HEAD request that includes a Content-Length or chunked transfer encoding causes the parser to skip reading the body, leading to request desynchronization and potential integrity impacts on downstream systems. An attacker can exploit this to inject or corrupt request routing by sending a HEAD request with a body, causing the parser to misalign subsequent requests in the stream.