nvm-sh nvm up to 0.40.5 Alias File index.tab NVM_DIR path traversal

Summaryinfo

A vulnerability marked as critical has been reported in nvm-sh nvm up to 0.40.5. Affected by this vulnerability is an unknown functionality of the file index.tab of the component Alias File Handler. Performing a manipulation of the argument NVM_DIR results in path traversal. This vulnerability is reported as CVE-2026-15921. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability classified as critical has been found in nvm-sh nvm up to 0.40.5. This affects an unknown code of the file index.tab of the component Alias File Handler. The manipulation of the argument NVM_DIR with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-23. The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Node Version Manager (nvm) is a POSIX-compliant shell function for managing multiple node.js versions. In versions 0.32.1 through 0.40.5, `nvm ls-remote` (and other commands that refresh remote LTS aliases, such as `nvm install --lts`) parse the node.js mirror's `index.tab` and use each release's LTS codename field as an alias filename without validating it. A malicious, compromised, or man-in-the-middled mirror can return an LTS codename containing path-traversal sequences such as `../../../.bashrc`, causing nvm to write the associated version string to a path outside `$NVM_DIR/alias`. With the default layout (`$NVM_DIR` is `~/.nvm`), this can create or overwrite files in the user's home directory, including shell startup files, which can lead to code execution in a later shell session. Exploitation requires the victim to use a hostile mirror -- via a compromised mirror or CDN, a network man-in-the-middle, or a maliciously configured `NVM_NODEJS_ORG_MIRROR`/`NVM_IOJS_ORG_MIRROR` -- and to run an affected command. Version 0.40.6 validates remote LTS codenames as safe alias filenames and rejects `..` path components when writing alias files.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-15921 since 07/15/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

Upgrading to version 0.40.6 eliminates this vulnerability.

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Productinfo

Vendor

• nvm-sh

Name

• nvm

Version

• 0.40.0
• 0.40.1
• 0.40.2
• 0.40.3
• 0.40.4
• 0.40.5

Website

• Product: https://github.com/nvm-sh/nvm/

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