CVE-2019-20477
CVSS v3
9.8
CRITICAL
EPSS Score
5.1 %
exploit probability, as of 2026-09-25
CISA KEV
No
known exploited
Exploitation
—
SSVC status
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.
Technical details
- Published
- 2020-02-19
Frequently asked questions
What is CVE-2019-20477?
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.
Is CVE-2019-20477 actively exploited?
Active exploitation of CVE-2019-20477 has not been confirmed. Its EPSS score was 5.1% on 2026-09-25, the estimated probability of exploitation in the next 30 days.
What is the CVSS score for CVE-2019-20477?
CVE-2019-20477 has a CVSS v3 base score of 9.8 (CRITICAL severity).
Is CVE-2019-20477 affecting your environment?
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