CVE-2026-121748

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CVE-2026-121748

Summary: nvm use --delete-prefix lets a project .npmrc choose which file npm rewrites or makes world-writable

Details: Node Version Manager (nvm) is a POSIX-compliant shell function for managing multiple node.js versions. In versions 0.27.0 through 0.40.8, when a project's `.npmrc` sets `prefix`, `nvm use` tells the user to run `nvm use --delete-prefix`, which runs `npm config delete prefix` and `npm config delete globalconfig` in the current directory without naming a config file. npm loads the project `.npmrc` before deciding which file to edit, so that file chooses the target: `userconfig=~/.bashrc` makes npm rewrite `~/.bashrc` as ini (corrupting it), and `location=global` with `globalconfig=` leaves the chosen file at mode 0666, which on a shared machine lets another local user write to it. The attacker (the author of a cloned repository or archive, or a local user who can write a shared parent directory) chooses the file but not the bytes written, and no project code runs. Version 0.41.0 no longer lets a project `.npmrc` select which config file `--delete-prefix` edits.

References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/121xxx/CVE-2026-121748.json, https://github.com/nvm-sh/nvm/security/advisories/GHSA-ccgf-7gv4-xg5h, https://nvd.nist.gov/vuln/detail/CVE-2026-121748, https://github.com/nvm-sh/nvm/commit/4049296ca8eef2067517d8cfd5ef5c0e615daa10, https://github.com/nvm-sh/nvm