CVE-2026-94185 in nvm
Summary
by MITRE • 09/21/2026
nvm resolves a requested version or alias by treating it as a filename under $NVM_DIR/alias. Before 0.40.8, nvm_alias() concatenated the requested name onto that directory and read the result with no containment check, so a name containing a `..` component escaped the alias directory; under the default layout an alias such as `../../.npmrc` resolves to a file in the user's home directory. nvm_print_alias_file() then emits every non-comment, non-empty line of whatever was opened. A version string taken from an untrusted .nvmrc reaches this path, so a developer who runs `nvm use`, `nvm install`, or `nvm which` inside an attacker-supplied repository discloses the first non-comment line of an arbitrary file readable by that user, in the resulting "is not yet installed" error message. A user-supplied `nvm alias <traversing-name>` discloses every non-comment line of the target file. There is no integrity or availability impact, and no command execution on this path.
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Analysis
by VulDB Data Team • 09/21/2026
The vulnerability identified involves a directory traversal flaw within the Node Version Manager (nvm) utility prior to version 0.40.8. The core issue resides in the nvm_alias function, which is responsible for resolving requested node versions or aliases by treating them as filenames located under the $NVM_DIR/alias directory. In vulnerable versions, this function concatenates the user-provided name directly onto the alias directory path without performing any containment checks to ensure the resulting file path remains within the intended directory structure. This lack of input validation allows an attacker to manipulate the filename using standard relative path components, specifically double dots (..), to escape the designated alias directory and access files located elsewhere in the filesystem hierarchy.
Under default installation layouts, this flaw enables significant information disclosure capabilities for a user who executes nvm commands within a repository controlled by an adversary. For instance, if a developer runs commands such as nvm use, nvm install, or nvm which inside a malicious project that contains a crafted .nvmrc file, the tool attempts to resolve the version specified in that file. If the content of this file includes path traversal sequences like ../../.npmrc, the system interprets this not as an alias but as a reference to a file located in the user's home directory. Consequently, when nvm fails to find the requested node version because it is not installed, it generates an error message that inadvertently reveals the contents of the targeted arbitrary file. Specifically, the function nvm_print_alias_file emits every non-comment and non-empty line from whatever file was opened during this resolution process.
The impact of this vulnerability is primarily limited to confidentiality rather than integrity or availability. An attacker can leverage this flaw to read sensitive configuration files, environment variables stored in dotfiles, or other private data accessible by the user running nvm. For example, reading .npmrc could expose registry tokens or authentication credentials used for package management. Similarly, accessing other hidden files could reveal SSH keys, API secrets, or personal project configurations. It is important to note that this vulnerability does not lead to remote code execution or arbitrary command execution on the target system. The attack vector relies on social engineering or physical access to trick a user into running nvm commands in a malicious directory structure, making it an issue of local privilege escalation regarding data exposure rather than full system compromise.
To mitigate this risk, users should upgrade nvm to version 0.40.8 or later, where the path resolution logic has been hardened to prevent directory traversal attacks by validating that resolved paths remain within the expected alias directory boundaries. In environments where upgrading is not immediately feasible, administrators and developers can adopt defensive practices such as avoiding the execution of nvm commands in untrusted repositories and ensuring that sensitive files are stored with restrictive permissions that limit access even if path traversal occurs. This incident highlights the importance of strict input validation when handling file paths derived from external sources, a principle central to preventing CWE-22 Improper Limitation of a Pathname to a Restricted Directory vulnerabilities as defined by industry standards. Furthermore, this type of local information disclosure aligns with techniques observed in ATT&CK frameworks related to data staging and collection via local scripts or utilities that process untrusted input without adequate sanitization.