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RubyGems Delete directory using symlink when decompressing tar

High severity GitHub Reviewed Published Jun 20, 2019 to the GitHub Advisory Database • Updated Aug 28, 2023

Package

bundler rubygems-update (RubyGems)

Affected versions

>= 2.7.6, < 2.7.9
>= 3.0.0, < 3.0.3

Patched versions

2.7.9
3.0.3

Description

A Directory Traversal issue was discovered in RubyGems 2.7.6 and later through 3.0.2. Before making new directories or touching files (which now include path-checking code for symlinks), it would delete the target destination. If that destination was hidden behind a symlink, a malicious gem could delete arbitrary files on the user's machine, presuming the attacker could guess at paths. Given how frequently gem is run as sudo, and how predictable paths are on modern systems (/tmp, /usr, etc.), this could likely lead to data loss or an unusable system.

References

Reviewed Jun 20, 2019
Published to the GitHub Advisory Database Jun 20, 2019
Last updated Aug 28, 2023

Severity

High

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
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
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:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H

EPSS score

0.605%
(79th percentile)

Weaknesses

CVE ID

CVE-2019-8320

GHSA ID

GHSA-5x32-c9mf-49cc

Source code

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