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PyYAML insecurely deserializes YAML strings leading to arbitrary code execution

Critical severity GitHub Reviewed Published Jan 4, 2019 to the GitHub Advisory Database • Updated Sep 5, 2023

Package

pip pyyaml (pip)

Affected versions

< 4.1

Patched versions

4.1

Description

In PyYAML before 4.1, the yaml.load() API could execute arbitrary code. In other words, yaml.safe_load is not used.

References

Published to the GitHub Advisory Database Jan 4, 2019
Reviewed Jun 16, 2020
Last updated Sep 5, 2023

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

1.419%
(87th percentile)

Weaknesses

CVE ID

CVE-2017-18342

GHSA ID

GHSA-rprw-h62v-c2w7

Source code

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