| Description | Node Version Manager (nvm) is a POSIX-compliant shell function for managing multiple node.js versions. In versions 0.40.0 through 0.40.8, `nvm use --save` and `nvm install --save` (or `-w`) write the resolved version to `$PWD/.nvmrc` with `tee`, which follows a symbolic link. A repository that commits `.nvmrc` as a symlink to a path outside itself (git recreates the link on clone) therefore makes `--save` truncate any file the user can write, such as a shell startup file or `~/.ssh/authorized_keys`, and replace its contents with the version string, or create the target of a dangling link; the link itself is left unchanged, so `git status` stays clean. The attacker does not control the content written, so this is data loss, not code execution. Version 0.41.0 refuses, with a warning, to write when `.nvmrc` in the current directory is a symlink, dangling or not, rather than writing through it or replacing it. |