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CVE-2017-18342

33
FAUCET Score

CVE-2017-18342 describes a critical deserialization vulnerability in PyYAML versions prior to 5.1, where the yaml.load() API could execute arbitrary code when processing untrusted data. This flaw impacts various Fedora Project distributions and PyYAML itself. With a CVSS score of 9.8 (CRITICAL), this vulnerability presents a significant risk due to its network-based attack vector, low attack complexity, and potential for complete compromise of confidentiality, integrity, and availability. While no active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion has been observed, organizations using affected PyYAML versions should prioritize upgrading to mitigate this severe risk.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.1CPE matchmatch criteria
cpe:2.3:a:pyyaml:pyyaml:*:*:*:*:*:*:*:*
28CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:28:*:*:*:*:*:*:*
29CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:29:*:*:*:*:*:*:*
30CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:30:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
5.61%
Probability of exploitation in next 30 days
EPSS Percentile
92.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0561 is in the 87th percentile among its peer group of 36,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (17)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: PyYAMLFixed in: 5.1
pippatch availablevia ghsa
Product: pyyamlFixed in: 4.1
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux OpenStack Platform 7 (Kilo)Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat Enterprise MRG 2Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 10 (Newton)Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 12 (Pike)Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 13 (Queens)Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 8 (Liberty)Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat OpenStack Platform 9 (Mitaka)Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat Satellite 5Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat Software CollectionsFixed in: python27-PyYAML
redhatend of lifevia redhat_api
Product: Red Hat Software CollectionsFixed in: rh-python36-PyYAML
redhatend of lifevia redhat_api
Product: Red Hat Ceph Storage 1.3Fixed in: PyYAML
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 6Fixed in: PyYAML

Vendor Advisories (2)

pipGHSA-rprw-h62v-c2w7critical

PyYAML insecurely deserializes YAML strings leading to arbitrary code execution

Jan 4, 2019
redhatCVE-2017-18342Important

PyYAML: yaml.load() API could execute arbitrary code

Jun 27, 2018

References

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