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Vulnerabilities

Vulnerability · CVE-2020-1747

A vulnerability was discovered in the PyYAML library in versions before 5.3.1, where it is susceptible to arbitrary code execution when it processes untrusted YAML fil…

Published Mar 24, 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-2020-1747. EPSS is 5.44%. 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
5.44%
Remediation
Version ranges on file
Affected products
cpe fedoraproject/fedora · cpe opensuse/leap · cpe oracle/communications cloud native core network function cloud native environment · cpe pyyaml/pyyaml

A vulnerability was discovered in the PyYAML library in versions before 5.3.1, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be vulnerable to this flaw. An attacker could use this flaw to execute arbitrary code on the system by abusing the python/object/new constructor.

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 fedoraproject/fedora32
  • cpe opensuse/leap15.1
  • cpe oracle/communications cloud native core network function cloud native environment22.1.0
  • cpe pyyaml/pyyaml< 5.3.1

How to fix CVE-2020-1747

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-2020-1747. EPSS is 5.44%. Act only if a listed version of the affected product is installed.

Which versions are affected?

Compare what you have installed with oracle/communications cloud native core network function cloud native environment 22.1.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-20: Improper Input Validation. EPSS 5.44%. 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. Mar 24, 2020 · Monitored products — high

    Detected

    A vulnerability was discovered in the PyYAML library in versions before 5.3.1, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be vulnerable to this flaw. An attacker could use this flaw to execute arbitrary code on the system by ab

  2. Jun 17, 2026 · Monitored products — high

    Updated

    A vulnerability was discovered in the PyYAML library in versions before 5.3.1, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be vulnerable to this flaw. An attacker could use this flaw to execute arbitrary code on the system by ab

Sources

  • CVE.orgVulnerability recordCVE-2020-1747

    Official CVE identifier

    cve.org
  • Monitored products — highVendor advisoryCVE-2020-1747

    A vulnerability was discovered in the PyYAML library in versions before 5.3.1, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be vulnerable to this flaw. An attacker could use this flaw to execute arbitrary code on the system by ab

    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