#VU33151 Inconsistent interpretation of HTTP requests in waitress - CVE-2019-16785
Vulnerability identifier: #VU33151
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: CVE-2019-16785
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 implemented a "MAY" part of the RFC7230 which states: "Although the line terminator for the start-line and header fields is the sequence CRLF, a recipient MAY recognize a single LF as a line terminator and ignore any preceding CR." Unfortunately if a front-end server does not parse header fields with an LF the same way as it does those with a CRLF it can lead to the front-end and the back-end server parsing the same HTTP message in two different ways. This can lead to a potential for HTTP request smuggling/splitting whereby Waitress may see two requests while the front-end server only sees a single HTTP message. This issue is fixed in Waitress 1.4.0.
Mitigation
Install update from vendor's website.
Vulnerable software versions
waitress: 1.4.0
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/8eba394ad75deaf9e5cd15b78a3d16b12e6b0eba
https://github.com/Pylons/waitress/security/advisories/GHSA-pg36-wpm5-g57p
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.
