CVE-2019-20477
CRITICAL9.8EPSS 0.42%Deserialization of Untrusted Data in PyYAML
Published: 4/20/2021Modified: 4/28/2026
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 packages (3)
- Debian/pyyamlfrom 0, < 5.2-1
- PyPI/pyyaml>= 5.1, < 5.2
- PyPI/pyyaml>= 5.1, < 5.2b1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| osv | CVSS 3.1 | CRITICAL9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
References (11)
- ADVISORYhttps://github.com/advisories/GHSA-3pqx-4fqf-j49f
- ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2019-20477
- ADVISORYhttps://security-tracker.debian.org/tracker/CVE-2019-20477
- PATCHhttps://github.com/yaml/pyyaml
- WEBhttps://github.com/pypa/advisory-database/tree/main/vulns/pyyaml/PYSEC-2020-176.yaml
- WEBhttps://github.com/yaml/pyyaml/blob/master/CHANGES
- WEBhttps://lists.fedoraproject.org/archives/list/[email protected]/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN
- WEBhttps://lists.fedoraproject.org/archives/list/[email protected]/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN/
- WEBhttps://lists.fedoraproject.org/archives/list/[email protected]/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H
- WEBhttps://lists.fedoraproject.org/archives/list/[email protected]/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H/
- WEBhttps://www.exploit-db.com/download/47655