Arbitrary File Creation, Arbitrary File Overwrite, Arbitrary Code Execution
@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 accomplished by extracting package contents into a project's node_modules
folder.
If the node_modules
folder of the root project or any of its dependencies is somehow replaced with a symbolic link, it could allow Arborist to write package dependencies to any arbitrary location on the file system.
Note that symbolic links contained within package artifact contents are filtered out, so another means of creating a node_modules
symbolic link would have to be employed.
preinstall
script could replace node_modules
with a symlink. (This is prevented by using --ignore-scripts
.)npm install --ignore-scripts
in the root. This may be successful, because npm install --ignore-scripts
is typically not capable of making changes outside of the project directory, so it may be deemed safe.2.8.2 (included in npm v7.20.7 and above)
Do not run npm install
on untrusted codebases, without first ensuring that the node_modules
directory in the project is not a symbolic link.
Prior to extracting any package contents, the node_modules
folder into which it is extracted is verified to be a real directory. If it is not, then it is removed.
Caveat: if you are currently relying on creating a symbolic link to the node_modules
folder in order to share dependencies between projects, then that will no longer be possible. Please use the npm link
command, explicit file:...
dependencies, and/or workspaces
to share dependencies in a development environment.
{ "nvd_published_at": "2021-08-31T17:15:00Z", "github_reviewed_at": "2021-08-31T16:03:00Z", "severity": "HIGH", "github_reviewed": true, "cwe_ids": [ "CWE-59", "CWE-61" ] }