Deserialization Issue in PyYAML Leading to Potential Code Execution
CVE-2019-20477

9.8CRITICAL

Key Information:

Vendor

Pyyaml

Status
Pyyaml
Vendor
CVE Published:
19 February 2020

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2019-20477?

PyYAML versions 5.1 through 5.1.2 contain a deserialization vulnerability linked to insufficient restrictions in the load and load_all functions. This flaw could allow attackers to exploit the Popen class in the subprocess module, leading to potential execution of arbitrary code. The issue arises from the inadequate resolution of a previous vulnerability (CVE-2017-18342), highlighting the need for users to update to more secure versions of the library.

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.

CVE-2019-20477 - Proof of Concept

References

https://github.com/yaml/pyyaml/blob/master/CHANGES
x_refsource_MISC
https://www.exploit-db.com/download/47655
x_refsource_MISC
https://lists.fedoraproject.org/archives/list/package-ann...
vendor-advisoryx_refsource_FEDORA

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

.