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Ubuntu 20.04 LTS : PyYAML vulnerability (USN-4940-1)

critical Nessus Plugin ID 149417

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Synopsis

The remote Ubuntu host is missing a security update.

Description

The remote Ubuntu 20.04 LTS / 20.10 host has packages installed that are affected by a vulnerability as referenced in the USN-4940-1 advisory.

 - 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. (CVE-2020-14343)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the affected python-yaml and / or python3-yaml packages.

See Also

https://ubuntu.com/security/notices/USN-4940-1

Plugin Details

Severity: Critical

ID: 149417

File Name: ubuntu_USN-4940-1.nasl

Version: 1.5

Type: local

Agent: unix

Published: 5/12/2021

Updated: 10/23/2023

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.4

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.4

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2020-14343

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:python-yaml, p-cpe:/a:canonical:ubuntu_linux:python3-yaml

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Ease: No known exploits are available

Patch Publication Date: 5/10/2021

Vulnerability Publication Date: 1/21/2021

Reference Information

CVE: CVE-2020-14343

IAVA: 2021-A-0463

USN: 4940-1