Remote code execution in PyYAML for Python

Published: 2021-07-04 | Updated: 2021-07-10
Risk High
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2020-14343
Exploitation vector Network
Public exploit Public exploit code for vulnerability #1 is available.
Vulnerable software
Web applications / Modules and components for CMS

Vendor The YAML Project

Security Bulletin

This security bulletin contains one high risk vulnerability.

1) Input validation error

EUVDB-ID: #VU54520

Risk: High


CVE-ID: CVE-2020-14343

CWE-ID: CWE-20 - Improper Input Validation

Exploit availability: Yes


The vulnerability allows a remote attacker to compromise the affected system.

The vulnerability exists due to insufficient validation of user-supplied input when processing untrusted YAML files through the full_load method or with the FullLoader loader. A remote attacker can pass specially crafted input to the application and execute arbitrary code on the system by abusing the python/object/new constructor.

Note, the vulnerability exists due to incomplete patch for vulnerability #VU25823.


Install updates from vendor's website.

Vulnerable software versions

PyYAML: 5.1 - 5.3.1

CPE2.3 External links

Q & A

Can this vulnerability be exploited remotely?

Is there known malware, which exploits this vulnerability?