← Vulnerability feed

Vulnerability record · CVE-2019-20477 · published 19 February 2020

CVE-2019-20477: Pyyaml deserialization of untrusted data vulnerability

Pyyaml · Pyyaml

PyYAML 5.1 through 5.1.2 has insufficient restrictions on the load and load_all functions because of a class deserialization issue, e.g., Popen is a class in the subprocess module. NOTE: this issue exists because of an incomplete fix for CVE-2017-18342.

9.8 CVSS 3.1 Critical EPSS 5.1% · top 7.9% CWE-502 · Deserialization of untrusted data
9.8CVSS 3.1 base score, v2 7.5
5.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
8References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

PyYAML 5.1 through 5.1.2 has insufficient restrictions on the load and load_all functions because of a class deserialization issue, e.g., Popen is a class in the subprocess module. NOTE: this issue exists because of an incomplete fix for CVE-2017-18342.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/yaml/pyyaml/blob/master/CHANGES Release NotesThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNF
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICC
https://www.exploit-db.com/download/47655 ExploitThird Party AdvisoryVDB Entry
https://github.com/yaml/pyyaml/blob/master/CHANGES Release NotesThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNF
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICC
https://www.exploit-db.com/download/47655 ExploitThird Party AdvisoryVDB Entry

Track CVE-2019-20477 inside VULONE

Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.

Start free Open in platform

Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

10.0CVE-2021-44228Apache Log4j2 JNDI lookup remote code executionApache Log4j2 versions 2.0-beta9 through 2.15.0 (excluding 2.12.2, 2.12.3, and 2.3.1) do not protect against attacker-controlled LDAP and other JNDI …KEVEPSS 100%analysed9.8CVE-2024-4577PHP-CGI on Windows argument injection leads to remote code executionPHP-CGI on Windows can misinterpret characters in the command line passed to Win32 API functions when certain code pages are configured, due to Windo…KEVEPSS 100%analysed9.8CVE-2021-44026Roundcube Webmail SQL injection via search parametersRoundcube Webmail before 1.3.17 and 1.4.x before 1.4.12 is prone to SQL injection through the search or search_params input. The flaw is remotely rea…KEVEPSS 70%analysed9.8CVE-2021-42013Apache HTTP Server path traversal and RCE via incomplete fixThe fix for CVE-2021-41773 in Apache HTTP Server 2.4.50 was insufficient, leaving a path traversal flaw that lets attackers map URLs to files outside…KEVEPSS 100%analysed9.8CVE-2021-41773Apache HTTP Server 2.4.49 path traversal and RCEA path normalization flaw introduced in Apache HTTP Server 2.4.49 lets attackers map URLs to files outside directories configured by Alias-like direc…KEVEPSS 100%analysed9.8CVE-2021-1870Apple WebKit logic flaw allows remote code executionA logic issue in Apple's WebKit was addressed with improved restrictions, affecting macOS Big Sur, Catalina, Mojave, iOS and iPadOS, plus WebKitGTK a…KEVEPSS 7.7%analysed9.8CVE-2021-1871Apple WebKit logic flaw allows remote code executionA logic issue in Apple's WebKit was addressed with improved restrictions. It affects macOS Big Sur, Catalina, Mojave, iOS and iPadOS, and a remote at…KEVEPSS 7.0%analysed9.8CVE-2020-16846SaltStack Salt API shell injection via crafted web requestsSaltStack Salt through 3002 is vulnerable to OS command injection when the SSH client is enabled and crafted web requests are sent to the Salt API. T…KEVEPSS 100%analysed

Source: NIST National Vulnerability Database (record CVE-2019-20477), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.