Executive brief
The 'tmp' library, a popular tool for creating temporary files and directories in Node.js applications, contains a security flaw. If an application allows users to influence the names or locations of temporary files, an attacker can trick the system into creating files in unauthorized locations outside of the intended temporary folder. This could allow an attacker to overwrite sensitive configuration files, plant malicious scripts, or disrupt system operations.
Technical details
A path traversal vulnerability exists in the 'tmp' npm package due to insufficient sanitization of the 'prefix', 'postfix', and 'dir' options. The library uses 'path.join()' to construct file paths by concatenating these user-supplied strings with the temporary directory path. Because 'path.join()' normalizes traversal sequences like '../', an attacker can escape the designated temporary directory. This allows for arbitrary file creation at attacker-controlled locations with the privileges of the Node.js process. The vulnerability is fixed in version 0.2.6.
Affected products
- raszi tmp < 0.2.6
Timeline
- 2026-05-26: advisory: GitHub Security Advisory published
- 2026-06-11: disclosed: NVD publication date
- 2026-06-11: patched: Fix released in version 0.2.6