PYSEC-2026-1103

vendorUSosv

aiohttp allows request smuggling due to incorrect parsing of chunk extensions

view advisory published 2026-07-07Licence: CC-BY-4.0

### Summary The Python parser parses newlines in chunk extensions incorrectly which can lead to request smuggling vulnerabilities under certain conditions. ### Impact If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or `AIOHTTP_NO_EXTENSIONS` is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections. ----- Patch: https://github.com/aio-libs/aiohttp/commit/259edc369075de63e6f3a4eaade058c62af0df71

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describes (1)

Related CVEs.

IDseverity exploitable
CVE-2024-52304UShigh7.5—
aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.10.11, the Python parser parses newlines in chunk extensions incorrectly which ca…
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