CRLF injection in urllib3 library

1) CRLF injection

EUVDB-ID: #VU47403

Risk: Medium

CVSSv3.1: 4.4 [CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-26137

CWE-ID: CWE-93 - Improper Neutralization of CRLF Sequences ('CRLF Injection')

Exploit availability: No

Description

The vulnerability allows a remote attacker to inject arbitrary data in server response.

The vulnerability exists due to insufficient validation of attacker-supplied data passed via the "method" parameter. A remote authenticated attacker can pass specially crafted data to the application containing CR-LF characters and modify application behavior.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

urllib3: 1.17 - 1.25.8

External links

http://bugs.python.org/issue39603
http://github.com/urllib3/urllib3/commit/1dd69c5c5982fae7c87a620d487c2ebf7a6b436b
http://github.com/urllib3/urllib3/pull/1800

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.