PT-2020-10462 · None+6 · Pyyaml+6

Published 2019-11-18 · Updated 2022-01-01 · CVE-2019-20477

Positive Technologies (AI Summary)

CVSS v3.1

9.8

Critical

Base vector

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

Name of the Vulnerable Software and Affected Versions PyYAML versions 5.1 through 5.1.2

Description The issue is related to insufficient restrictions on the load and load all functions in PyYAML due to a class deserialization problem. This can be exploited, for example, through the Popen class in the subprocess module. The problem arose from an incomplete fix for a previous issue.

Recommendations For PyYAML versions 5.1 through 5.1.2, consider disabling the use of the load and load all functions until a proper fix is available. Restrict the deserialization of classes to minimize the risk of exploitation. At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Exploit

Deserialization of Untrusted Data

Weakness Enumeration

CWE-502

Related Identifiers

ALSA-2020:4641

ALT-PU-2021-1521

ALT-PU-2021-1534

CESA-2020_4641

CVE-2019-20477

GHSA-3PQX-4FQF-J49F

PYSEC-2020-176

RHSA-2020:4641

RHSA-2020_4641

RLSA-2020:4641

Affected Products

Alt Linux

Almalinux

Astra Linux

Centos

Pyyaml

Red Hat

Rocky Linux

References · 35

• 🔥 https://exploit-db.com/download/47655 · Exploit
• https://osv.dev/vulnerability/GHSA-3pqx-4fqf-j49f · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/[e-mail]/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2019-20477 · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN · Vendor Advisory
• https://linux.oracle.com/errata/ELSA-2020-4641.html · Vendor Advisory
• https://errata.rockylinux.org/RLSA-2020:4641 · Vendor Advisory
• https://ubuntu.com/security/CVE-2019-20477 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2019-20477 · Security Note
• https://errata.almalinux.org/8/ALSA-2020-4641.html · Vendor Advisory
• https://osv.dev/vulnerability/RLSA-2020:4641 · Vendor Advisory
• https://osv.dev/vulnerability/PYSEC-2020-176 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2019-20477 · Security Note
• https://security-tracker.debian.org/tracker/CVE-2019-20477 · Vendor Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H · Vendor Advisory