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.
github.com/yaml/pyyaml
github.com/yaml/pyyaml/blob/master/CHANGES
lists.fedoraproject.org/archives/list/[email protected]/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN
lists.fedoraproject.org/archives/list/[email protected]/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H
nvd.nist.gov/vuln/detail/CVE-2019-20477
www.exploit-db.com/download/47655