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Vulnerabilities

Vulnerability · CVE-2017-18342

In PyYAML before 5.1, the yaml.load() API could execute arbitrary code if used with untrusted data.

Published Jun 27, 2018 · catalog updated Jun 17, 2026 · In PyYAML before 5.1,

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

Open the advisory

Exploitation likelihood is not on this record for CVE-2017-18342. A missing EPSS score is not a low risk. Compare In PyYAML before 5.1, with the linked advisory before you change production.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (In PyYAML before 5.1,).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
  • EPSS is missing. A missing score is not a low risk.

Same product and reporting

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

In PyYAML before 5.1, the yaml.load() API could execute arbitrary code if used with untrusted data. The load() function has been deprecated in version 5.1 and the 'UnsafeLoader' has been introduced for backward compatibility with the function.

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/fedora28
  • cpe fedoraproject/fedora29
  • cpe fedoraproject/fedora30
  • cpe pyyaml/pyyaml< 5.1

How to fix CVE-2017-18342

  • Upgrade

    CVE-2017-18342 lists a fix boundary at 5.1. Compare the installed build with that boundary before you change production.

  • Version check

    Affected < 5.1

  • Advisory

    Open the inventory_high record and follow its fix.

  • Official advisories

What to do

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

Should you patch?

Exploitation likelihood is not on this record for CVE-2017-18342. A missing EPSS score is not a low risk. Compare In PyYAML before 5.1, with the linked advisory before you change production.

Which versions are affected?

Compare what you have installed with 28, 29, 30, < 5.1. 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 is not on this record yet. 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. Jun 27, 2018 · Monitored products — high

    Detected

    In PyYAML before 5.1, the yaml.load() API could execute arbitrary code if used with untrusted data. The load() function has been deprecated in version 5.1 and the 'UnsafeLoader' has been introduced for backward compatibility with the function.

  2. Jun 17, 2026 · Monitored products — high

    Updated

    In PyYAML before 5.1, the yaml.load() API could execute arbitrary code if used with untrusted data. The load() function has been deprecated in version 5.1 and the 'UnsafeLoader' has been introduced for backward compatibility with the function.

Sources

  • Monitored products — highVendor advisoryCVE-2017-18342

    In PyYAML before 5.1, the yaml.load() API could execute arbitrary code if used with untrusted data. The load() function has been deprecated in version 5.1 and the 'UnsafeLoader' has been introduced for backward compatibility with the function.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Jun 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Monitored products — highNov 8, 2026