Bug 2567775 (CVE-2026-121746)

Summary: CVE-2026-121746 nvm: nvm: Arbitrary file overwrite via insecure symbolic link handling
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in Node Version Manager (nvm). When saving a version configuration, nvm follows symbolic links without verifying whether the target file resides outside the working directory. By convincing a user to execute save commands within a malicious repository containing a crafted symbolic link, an attacker can overwrite arbitrary files accessible to that user. Successful exploitation replaces target file contents with version details, leading to data loss.
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Description OSIDB Bzimport 2026-11-05 22:25:06 UTC 
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.