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Vulnerabilities

Vulnerability · CVE-2019-20477

CVE-2019-20477 is listed by 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., P…

Published Feb 19, 2020 · catalog updated Jun 17, 2026 · the affected product

Last checked Nov 8, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2019-20477. EPSS is 5.11%. Act only if a listed version of the affected product is installed.

Gaps on this record

  • No plain product name is stored. The page cannot tell you which product to check.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Critical9.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
5.11%
Remediation
Version ranges on file
Affected products
cpe fedoraproject/fedora · cpe pyyaml/pyyaml

CVE-2019-20477 is listed by 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 th.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe fedoraproject/fedora30
  • cpe fedoraproject/fedora31
  • cpe pyyaml/pyyaml>= 5.1, <= 5.1.2

How to fix CVE-2019-20477

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2019-20477. EPSS is 5.11%. Act only if a listed version of the affected product is installed.

Which versions are affected?

Compare what you have installed with 30, 31, >= 5.1, <= 5.1.2. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-502: Deserialization of Untrusted Data. EPSS 5.11%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

PyYAML security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 19, 2020 · Monitored products — high

    Detected

    CVE-2019-20477 is listed by 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 th.

  2. Jun 17, 2026 · Monitored products — high

    Updated

    CVE-2019-20477 is listed by 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 th.

Sources

  • CVE.orgVulnerability recordCVE-2019-20477

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-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.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 8, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CVE.orgNov 8, 2026
  • Monitored products — highNov 8, 2026