CVE-2017-18342
In PyYAML before 5.1, the yaml.load() API could execute arbitrary code if used with untrusted data.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (5.66%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 5.66% probability · 93th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-502
- Affected
- pyyaml/pyyaml · fedoraproject/fedora
- Source
- cve@mitre.org
EPSS 5.7% since 27 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.