CVE-2020-14343

Publication date 9 February 2021

Last updated 24 July 2024

Ubuntu priority

Cvss 3 Severity Score

A vulnerability was discovered in the PyYAML library in versions before 5.4, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be vulnerable to this flaw. This flaw allows an attacker to execute arbitrary code on the system by abusing the python/object/new constructor. This flaw is due to an incomplete fix for CVE-2020-1747.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
pyyaml	21.04 hirsute	Fixed 5.3.1-3ubuntu1
	20.10 groovy	Fixed 5.3.1-2ubuntu0.1
	20.04 LTS focal	Fixed 5.3.1-1ubuntu0.1
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

sbeattie

incomplete fix of CVE-2020-1747

mdeslaur

FullLoader was introduced in 5.1. FullLoader should not be used on untrusted input.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
pyyaml	Upstream: 7adc0db

Severity score breakdown

Parameter	Value
Base score	9.8 · Critical
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	High
Integrity impact	High
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

USN-4940-1
PyYAML vulnerability
10 May 2021