Aiohttp has inconsistent interpretation of `Content-Length` vs. `Transfer-Encoding` differing in C and Python fallbacks
Impact
Aiohttp has a security vulnerability regarding the inconsistent interpretation of the http protocol. As we know that HTTP/1.1 is persistent, if we have both Content-Length(CL) and Transfer-Encoding(TE) it can lead to incorrect interpretation of two entities that parse the HTTP and we can poison other sockets with this incorrect interpretation.
A possible Proof-of-Concept (POC) would be a configuration with a reverse proxy(frontend) that accepts both CL and TE headers and aiohttp as backend. As aiohttp parses anything with chunked, we can pass a chunked123 as TE, the frontend entity will ignore this header and will parse Content-Length. I can give a Dockerfile with the configuration if you want.
The impact of this vulnerability is that it is possible to bypass any proxy rule, poisoning sockets to other users like passing Authentication Headers, also if it is present an Open Redirect (just like CVE-2021-21330) we can combine it to redirect random users to our website and log the request.
References
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Python (PyPI) | aiohttp | < 3.8.0 | 3.8.0 |
Referencias
- https://github.com/aio-libs/aiohttp/security/advisories/GHSA-xx9p-xxvh-7g8j
- https://github.com/aio-libs/aiohttp/commit/f016f0680e4ace6742b03a70cb0382ce86abe371
- https://nvd.nist.gov/vuln/detail/CVE-2023-47641
- https://github.com/aio-libs/aiohttp
- https://github.com/aio-libs/aiohttp/releases/tag/v3.8.0
- https://github.com/pypa/advisory-database/tree/main/vulns/aiohttp/PYSEC-2023-247.yaml
- https://lists.debian.org/debian-lts-announce/2025/02/msg00002.html
- Vector CVSS
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N- Debilidad (CWE)
CWE-444- Plataforma
- Python (PyPI)
- Paquete
aiohttp- Publicada
- 14.11.2023
- Actualizado
- 11.10.2026 12:19
Fuentes y licencias
OSV / GitHub Advisory Database - PYSEC-2023-247 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-xx9p-xxvh-7g8j - CC BY 4.0
Historial de vulnerabilidades: aiohttp
Todas las vulnerabilidades publicadas de este paquete (Python (PyPI)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 55
- Primera → última
- 02.2021 10.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 7
- Media 29
- Baja 19
Divulgaciones por año
- 2021: 1
- 2022: 0
- 2023: 6
- 2024: 7
- 2025: 1
- 2026: 40
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