ghsa-g2xc-35jw-c63p
Vulnerability from github
5.1 (Medium) - CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N
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, chunked
Would 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)
{ "affected": [ { "package": { "ecosystem": "PyPI", "name": "waitress" }, "ranges": [ { "events": [ { "introduced": "0" }, { "fixed": "1.4.0" } ], "type": "ECOSYSTEM" } ] } ], "aliases": [ "CVE-2019-16786" ], "database_specific": { "cwe_ids": [ "CWE-444" ], "github_reviewed": true, "github_reviewed_at": "2019-12-20T23:01:53Z", "nvd_published_at": "2019-12-20T23:15:00Z", "severity": "MODERATE" }, "details": "### Impact\n\nWaitress 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.\n\nAccording 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`.\n\nRequests sent with:\n\n```\nTransfer-Encoding: gzip, chunked\n```\n\nWould incorrectly get ignored, and the request would use a `Content-Length` header instead to determine the body size of the HTTP message.\n\nThis could allow for Waitress to treat a single request as multiple requests in the case of HTTP pipelining.\n\n### Patches\n\nThis 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. \n\nWaitress 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`.\n\nThe Pylons Project recommends upgrading as soon as possible, while validating that the changes in Waitress don\u0026#39;t cause any changes in behavior.\n\n### Workarounds\n\nVarious 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\u0026#39;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).\n\n### Issues/more security issues:\n\n* open an issue at https://github.com/Pylons/waitress/issues (if not sensitive or security related)\n* email the Pylons Security mailing list: pylons-project-security@googlegroups.com (if security related)", "id": "GHSA-g2xc-35jw-c63p", "modified": "2024-11-19T13:57:29Z", "published": "2019-12-20T23:04:18Z", "references": [ { "type": "WEB", "url": "https://github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p" }, { "type": "ADVISORY", "url": "https://nvd.nist.gov/vuln/detail/CVE-2019-16786" }, { "type": "WEB", "url": "https://github.com/Pylons/waitress/commit/f11093a6b3240fc26830b6111e826128af7771c3" }, { "type": "WEB", "url": "https://access.redhat.com/errata/RHSA-2020:0720" }, { "type": "WEB", "url": "https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes" }, { "type": "PACKAGE", "url": "https://github.com/Pylons/waitress" }, { "type": "WEB", "url": "https://github.com/pypa/advisory-database/tree/main/vulns/waitress/PYSEC-2019-137.yaml" }, { "type": "WEB", "url": "https://lists.debian.org/debian-lts-announce/2022/05/msg00011.html" }, { "type": "WEB", "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/GVDHR2DNKCNQ7YQXISJ45NT4IQDX3LJ7" }, { "type": "WEB", "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/LYEOTGWJZVKPRXX2HBNVIYWCX73QYPM5" }, { "type": "WEB", "url": "https://www.oracle.com/security-alerts/cpuapr2022.html" } ], "schema_version": "1.4.0", "severity": [ { "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N", "type": "CVSS_V3" }, { "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:L/SA:N", "type": "CVSS_V4" } ], "summary": "HTTP Request Smuggling: Invalid Transfer-Encoding in Waitress" }
Sightings
Author | Source | Type | Date |
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Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.