Bug 1999744 (CVE-2021-39134) - CVE-2021-39134 nodejs-arborist: symlink following vulnerability
Summary: CVE-2021-39134 nodejs-arborist: symlink following vulnerability
Keywords:
Status: NEW
Alias: CVE-2021-39134
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
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Depends On:
Blocks: 1999749
TreeView+ depends on / blocked
 
Reported: 2021-08-31 16:53 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-09-01 18:48 UTC (History)
1 user (show)

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A flaw was found in nodejs-arborist. On case-insensitive file systems (such as macOS and Windows), Arborist’s internal data structure did not see multiple dependencies as separate items that could coexist within the same level in the node_modules hierarchy when they differ only in the case of their name. This issue, combined with a symlink dependency such as file:/some/path, allows an attacker to create a situation in which arbitrary contents are written to any location on the filesystem. The highest threat from this vulnerability is to integrity and system availability.
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Description Guilherme de Almeida Suckevicz 2021-08-31 16:53:50 UTC
@npmcli/arborist, the library that calculates dependency trees and manages the node_modules folder hierarchy for the npm command line interface, aims to guarantee that package dependency contracts will be met, and the extraction of package contents will always be performed into the expected folder.

This is, in part, accomplished by resolving dependency specifiers defined in package.json manifests for dependencies with a specific name, and nesting folders to resolve conflicting dependencies.

When multiple dependencies differ only in the case of their name, Arborist's internal data structure saw them as separate items that could coexist within the same level in the node_modules hierarchy. However, on case-insensitive file systems (such as macOS and Windows), this is not the case. Combined with a symlink dependency such as file:/some/path, this allowed an attacker to create a situation in which arbitrary contents could be written to any location on the filesystem.

For example, a package pwn-a could define a dependency in their package.json file such as "foo": "file:/some/path". Another package, pwn-b could define a dependency such as FOO: "file:foo.tgz". On case-insensitive file systems, if pwn-a was installed, and then pwn-b was installed afterwards, the contents of foo.tgz would be written to /some/path, and any existing contents of /some/path would be removed.

Anyone using npm v7.20.6 or earlier on a case-insensitive filesystem is potentially affected.

Reference:
https://github.com/npm/arborist/security/advisories/GHSA-2h3h-q99f-3fhc


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