Arbitrary Code Execution in PyYAML Library Affecting Multiple Versions
CVE-2020-14343

9.8CRITICAL

Key Information:

Vendor

Pyyaml

Status
Pyyaml
Vendor
CVE Published:
9 February 2021

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2020-14343?

The PyYAML library, specifically in versions preceding 5.4, has a vulnerability allowing arbitrary code execution when handling untrusted YAML input via the full_load method or FullLoader. This weakness can be exploited by an attacker to execute malicious code on the affected system, taking advantage of the python/object/new constructor. This issue originates from an incomplete fix addressing a previous vulnerability (CVE-2020-1747), posing significant risks for applications utilizing this library to parse untrusted data.

Affected Version(s)

PyYAML PyYAML 5.4

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

loader-CVE-2020-14343
Created by j4k0m

Python-Example
Created by seal-sec-demo-2

References

https://github.com/yaml/pyyaml/issues/420
https://bugzilla.redhat.com/show_bug.cgi?id=1860466
https://www.oracle.com/security-alerts/cpuapr2022.html

EPSS Score

5% chance of being exploited in the next 30 days.

CVSS V3.1

Score:
9.8
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

.