#VU21781 Input validation error in PyYAML


Published: 2019-10-15

Vulnerability identifier: #VU21781

Vulnerability risk: High

CVSSv3.1: 7.1 [CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-18342

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
PyYAML
Web applications / Modules and components for CMS

Vendor: The YAML Project

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


External links
http://github.com/yaml/pyyaml/blob/master/CHANGES
http://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.


Latest bulletins with this vulnerability