nvm passes the version pattern to grep without -e, letting a .nvmrc inject grep options and read local files

Overview

Node Version Manager (nvm) is a POSIX-compliant shell function for managing multiple node.js versions. In versions 0.5.0 through 0.40.8, the requested version pattern is passed to grep as a bare argument, without -e, in nvm_ls_remote_index_tab, nvm_remote_version, and nvm_ls_cached. A .nvmrc whose first line starts with -, such as -Rohenpm_[A-Za-z0-9]*, is parsed as grep options; with GNU grep, -R searches the current directory recursively (following symlinks) instead of the version list. On a bare nvm install, nvm then treats a matched string from those files as the version, prints it, and requests it from the configured mirror inside download URLs, so for example a repository containing a symlink to ../../.npmrc can leak the user's npm token to the terminal and to the mirror's and any proxy's logs. The disclosure is read-only and limited to the characters 0-9A-Za-z._+-. Version 0.41.0 passes every version pattern to grep with -e.

Affected

• nvm >= 0.5.0 < 0.41.0

Remediation

Upgrade to nvm 0.41.0 or later.

Workarounds

Until upgrading, check that .nvmrc does not start with - before running nvm in an untrusted project directory.