Remote code execution in PyYAML component for Python

1) Input validation error

EUVDB-ID: #VU21781

Risk: High

CVSSv4.0: 7.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2017-18342

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code.

The vulnerability exists due to insufficient validation of user-supplied input in the "yaml.load()" API (yaml.safe_load is not used). A remote attacker can execute arbitrary code on the target system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

PyYAML: 3.01 - 3.13

CPE2.3

• cpe:2.3:a:the_yaml_project:pyyaml:3.01:*:*:*:*:python:*:*
• cpe:2.3:a:the_yaml_project:pyyaml:3.02:*:*:*:*:python:*:*
• cpe:2.3:a:the_yaml_project:pyyaml:3.03:*:*:*:*:python:*:*

External links

https://github.com/yaml/pyyaml/blob/master/CHANGES
https://github.com/yaml/pyyaml/pull/74

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.