Fedora 31 update for python-waitress

Published: 2020-02-16 | Updated: 2025-04-25

Risk	High
Patch available	YES
Number of vulnerabilities	3
CVE-ID	CVE-2019-16786 CVE-2019-16785 CVE-2019-16789
CWE-ID	CWE-444
Exploitation vector	Network
Public exploit	N/A
Vulnerable software	Fedora Operating systems & Components / Operating system python-waitress Operating systems & Components / Operating system package or component
Vendor	Fedoraproject

Security Bulletin

This security bulletin contains information about 3 vulnerabilities.

1) Inconsistent interpretation of HTTP requests

EUVDB-ID: #VU30507

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-2019-16786

CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

Exploit availability: No

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 updates from vendor's repository.

Vulnerable software versions

Fedora: 31

python-waitress: before 1.4.3-1.fc31

CPE2.3

External links

https://bodhi.fedoraproject.org/updates/FEDORA-2020-65a7744e38

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.

2) Inconsistent interpretation of HTTP requests

EUVDB-ID: #VU33151

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 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

Exploit availability: No

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 updates from vendor's repository.

Vulnerable software versions

Fedora: 31

python-waitress: before 1.4.3-1.fc31

CPE2.3

External links

https://bodhi.fedoraproject.org/updates/FEDORA-2020-65a7744e38

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.

3) Inconsistent interpretation of HTTP requests

EUVDB-ID: #VU33152

Risk: High

CVSSv4.0: 6.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2019-16789

CWE-ID: CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request Smuggling')

Exploit availability: No

Description

The vulnerability allows a remote non-authenticated attacker to read and manipulate data.

In Waitress through version 1.4.0, if a proxy server is used in front of waitress, an invalid request may be sent by an attacker that bypasses the front-end and is parsed differently by waitress leading to a potential for HTTP request smuggling. Specially crafted requests containing special whitespace characters in the Transfer-Encoding header would get parsed by Waitress as being a chunked request, but a front-end server would use the Content-Length instead as the Transfer-Encoding header is considered invalid due to containing invalid characters. If a front-end server does HTTP pipelining to a backend Waitress server this could lead to HTTP request splitting which may lead to potential cache poisoning or unexpected information disclosure. This issue is fixed in Waitress 1.4.1 through more strict HTTP field validation.

Mitigation

Install updates from vendor's repository.

Vulnerable software versions

Fedora: 31

python-waitress: before 1.4.3-1.fc31

CPE2.3

External links

https://bodhi.fedoraproject.org/updates/FEDORA-2020-65a7744e38

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.