aiohttp allows request smuggling due to incorrect parsing of chunk extensions
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
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | aiohttp | < 3.10.11 | 3.10.11 |
References
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-8495-4g3g-x7pr
- https://nvd.nist.gov/vuln/detail/CVE-2024-52304
- https://github.com/aio-libs/aiohttp/commit/259edc369075de63e6f3a4eaade058c62af0df71
- https://github.com/aio-libs/aiohttp
- https://lists.debian.org/debian-lts-announce/2025/02/msg00002.html
- https://pypi.org/project/aiohttp
- https://github.com/advisories/GHSA-8495-4g3g-x7pr
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X- Weakness (CWE)
CWE-444- Platform
- Python (PyPI)
- Package
aiohttp- Disclosed
- 18.11.2024
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-1103 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-8495-4g3g-x7pr - CC BY 4.0
Vulnerability history: aiohttp
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 55
- First → latest
- 02.2021 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 7
- Medium 29
- Low 19
Disclosures per year
- 2021: 1
- 2022: 0
- 2023: 6
- 2024: 7
- 2025: 1
- 2026: 40
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