HTTP Request Smuggling: Invalid Transfer-Encoding in Waitress
Impact
Waitress would parse the Transfer-Encoding header and only look for a single string value, if that value was not chunked it would fall through and use the Content-Length header instead.
According to the HTTP standard Transfer-Encoding should be a comma separated list, with the inner-most encoding first, followed by any further transfer codings, ending with chunked.
Requests sent with:
Transfer-Encoding: gzip, chunkedWould incorrectly get ignored, and the request would use a Content-Length header instead to determine the body size of the HTTP message.
This could allow for Waitress to treat a single request as multiple requests in the case of HTTP pipelining.
Patches
This issue is fixed in Waitress 1.4.0. This brings a range of changes to harden Waitress against potential HTTP request confusions, and may change the behaviour of Waitress behind non-conformist proxies.
Waitress will now return a 501 Not Implemented error if the Transfer-Encoding is not chunked or contains multiple elements. Waitress does not support any transfer codings such as gzip or deflate.
The Pylons Project recommends upgrading as soon as possible, while validating that the changes in Waitress don't cause any changes in behavior.
Workarounds
Various reverse proxies may have protections against sending potentially bad HTTP requests to the backend, and or hardening against potential issues like this. If the reverse proxy doesn't use HTTP/1.1 for connecting to the backend issues are also somewhat mitigated, as HTTP pipelining does not exist in HTTP/1.0 and Waitress will close the connection after every single request (unless the Keep Alive header is explicitly sent... so this is not a fool proof security method).
Issues/more security issues:
- open an issue at https://github.com/Pylons/waitress/issues (if not sensitive or security related)
- email the Pylons Security mailing list: pylons-project-security@googlegroups.com (if security related)
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Python (PyPI) | waitress | < 1.4.0 | 1.4.0 |
Referencias
- https://github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p
- https://github.com/Pylons/waitress/commit/f11093a6b3240fc26830b6111e826128af7771c3
- https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GVDHR2DNKCNQ7YQXISJ45NT4IQDX3LJ7/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LYEOTGWJZVKPRXX2HBNVIYWCX73QYPM5/
- https://access.redhat.com/errata/RHSA-2020:0720
- https://nvd.nist.gov/vuln/detail/CVE-2019-16786
- https://github.com/Pylons/waitress
- https://github.com/pypa/advisory-database/tree/main/vulns/waitress/PYSEC-2019-137.yaml
- https://lists.debian.org/debian-lts-announce/2022/05/msg00011.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GVDHR2DNKCNQ7YQXISJ45NT4IQDX3LJ7
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LYEOTGWJZVKPRXX2HBNVIYWCX73QYPM5
- https://www.oracle.com/security-alerts/cpuapr2022.html
- Vector CVSS
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N- Debilidad (CWE)
CWE-444- Plataforma
- Python (PyPI)
- Paquete
waitress- Publicada
- 20.12.2019
- Actualizado
- 11.10.2026 13:19
Fuentes y licencias
OSV / GitHub Advisory Database - PYSEC-2019-137 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-g2xc-35jw-c63p - CC BY 4.0
Historial de vulnerabilidades: waitress
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
- 10
- Primera → última
- 12.2019 10.2024
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Crítica 2
- Alta 4
- Media 4
Divulgaciones por año
- 2019: 5
- 2020: 1
- 2021: 0
- 2022: 2
- 2023: 0
- 2024: 2
- 2025: 0
- 2026: 0
-
HTTP Request Smuggling: Invalid Transfer-Encoding in Waitress esta entrada
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