CVE-2021-32804
Arbitrary File Creation/Overwrite due to insufficient absolute path sanitization
In short
The npm tar package doesn't properly remove absolute paths from files during extraction, allowing attackers to create or overwrite files anywhere on the system by using repeated slashes in file paths (like ////home/user/.bashrc).
Technical detail
Insufficient path sanitization in node-tar allows arbitrary file creation/overwrite when extracting tar archives with maliciously crafted absolute paths containing repeated root separators. The vulnerability exists because the code strips only a single leading slash, leaving subsequent slashes intact which resolve to absolute paths. An attacker can exploit this by providing a specially crafted tar archive without requiring the `preservePaths` flag to be enabled.
Summary generated and translated by AI from the official description.
The npm package "tar" (aka node-tar) before versions 6.1.1, 5.0.6, 4.4.14, and 3.3.2 has a arbitrary File Creation/Overwrite vulnerability due to insufficient absolute path sanitization. node-tar aims to prevent extraction of absolute file paths by turning absolute paths into relative paths when the `preservePaths` flag is not set to `true`. This is achieved by stripping the absolute path root from any absolute file paths contained in a tar file. For example `/home/user/.bashrc` would turn into `home/user/.bashrc`. This logic was insufficient when file paths contained repeated path roots such as `////home/user/.bashrc`. `node-tar` would only strip a single path root from such paths. When given an absolute file path with repeating path roots, the resulting path (e.g. `///home/user/.bashrc`) would still resolve to an absolute path, thus allowing arbitrary file creation and overwrite. This issue was addressed in releases 3.2.2, 4.4.14, 5.0.6 and 6.1.1. Users may work around this vulnerability without upgrading by creating a custom `onentry` method which sanitizes the `entry.path` or a `filter` method which removes entries with absolute paths. See referenced GitHub Advisory for details. Be aware of CVE-2021-32803 which fixes a similar bug in later versions of tar.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N