#VU18829 CRLF injection in Python - CVE-2019-9740

Vulnerability identifier: #VU18829

Vulnerability risk: Medium

CVSSv4.0: 2.9 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2019-9740

CWE-ID: CWE-93

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Python
Universal components / Libraries / Scripting languages

Vendor: Python.org

Description

The vulnerability allows a remote attacker to perform CRLF injection attacks.

The vulnerability exists within urllib2 implementation for Python 2.x and urllib3 implementation for Python 3.x when processing the path component of a URL after the "?" character within the urllib.request.urlopen() call. A remote attacker with ability to control URL, passed to the application, can use CRLF sequences to split the HTTP request and inject arbitrary HTTP headers into request, made by the application.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Python: 2.7.0 - 2.7.2150, 3.0.0 - 3.0.1, 3.1.0 - 3.1.2150, 3.2.0 - 3.2.2150, 3.3 - 3.3.7, 3.4 - 3.4.10, 3.5 - 3.5.7, 3.6 - 3.6.8, 3.7 - 3.7.3, 3.8

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External links
https://www.securityfocus.com/bid/107466
https://access.redhat.com/errata/RHSA-2019:1260
https://bugs.python.org/issue36276
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/JMWSKTNOHSUOT3L25QFJAVCFYZX46FYK/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/JXASHCDD4PQFKTMKQN4YOP5ZH366ABN4/

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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. However, proof of concept for this vulnerability is available.