CVE-2017-18342

Name: CVE-2017-18342
Creator: NVD / NIST
Published: 2018-06-27T12:29:00.21+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 6.08%

Last modified Jun 17, 2026

CVE-2017-18342 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 6.08% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

6.08%

92.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-502

Affected Software

Vendor	Product	Versions
Pyyaml	Pyyaml	< 5.1
Fedoraproject	Fedora	28
Fedoraproject	Fedora	29
Fedoraproject	Fedora	30

References

https://github.com/marshmallow-code/apispec/issues/278Third Party Advisory
https://github.com/yaml/pyyaml/blob/master/CHANGESRelease Notes, Third Party Advisory
https://github.com/yaml/pyyaml/issues/193Third Party Advisory
https://github.com/yaml/pyyaml/pull/74Patch, Third Party Advisory
https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load%28input%29-Deprecation
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JEX7IPV5P2QJITAMA5Z63GQCZA5I6NVZ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KSQQMRUQSXBSUXLCRD3TSZYQ7SEZRKCE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M6JCFGEIEOFMWWIXGHSELMKQDD4CV2BA/
https://security.gentoo.org/glsa/202003-45Third Party Advisory
https://github.com/marshmallow-code/apispec/issues/278Third Party Advisory
https://github.com/yaml/pyyaml/blob/master/CHANGESRelease Notes, Third Party Advisory
https://github.com/yaml/pyyaml/issues/193Third Party Advisory
https://github.com/yaml/pyyaml/pull/74Patch, Third Party Advisory
https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load%28input%29-Deprecation
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JEX7IPV5P2QJITAMA5Z63GQCZA5I6NVZ/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KSQQMRUQSXBSUXLCRD3TSZYQ7SEZRKCE/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M6JCFGEIEOFMWWIXGHSELMKQDD4CV2BA/
https://security.gentoo.org/glsa/202003-45Third Party Advisory

Timeline

Published: Jun 27, 2018
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2017-18342?

How severe is CVE-2017-18342?

CVE-2017-18342 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 6.08% probability of exploitation in the next 30 days.

How do I fix CVE-2017-18342?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2017-18342?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST