What’s Vulnerable › Vulnerabilities

CVE-2019-20477

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 5.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-02-19 · updated 2026-06-17
• Weakness: CWE-502

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.

Affected products

• Fedoraproject Fedora: 30, 31
• Pyyaml: from 5.1 through 5.1.2

References

• https://github.com/yaml/pyyaml/blob/master/CHANGES
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H/
• https://www.exploit-db.com/download/47655
• https://github.com/yaml/pyyaml/blob/master/CHANGES
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H/
• https://www.exploit-db.com/download/47655

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