#VU30507 Inconsistent interpretation of HTTP requests in waitress - CVE-2019-16786
Vulnerability identifier: #VU30507
Vulnerability risk: Medium
CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]
CVE-ID:
CWE-ID:
CWE-444
Exploitation vector: Network
Exploit availability: No
Vulnerable software:
waitress
Other software /
Other software solutions
Vendor: Pylons Project
Description
The vulnerability allows a remote non-authenticated attacker to manipulate data.
Waitress through version 1.3.1 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. This issue is fixed in Waitress 1.4.0.
Mitigation
Install update from vendor's website.
Vulnerable software versions
waitress: 1.3.0
External links
https://access.redhat.com/errata/RHSA-2020:0720
https://docs.pylonsproject.org/projects/waitress/en/latest/#security-fixes
https://github.com/Pylons/waitress/commit/f11093a6b3240fc26830b6111e826128af7771c3
https://github.com/Pylons/waitress/security/advisories/GHSA-g2xc-35jw-c63p
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/
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
