Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning
Impact
Arbitrary File Creation, Arbitrary File Overwrite, Arbitrary Code Execution
node-tar aims to guarantee that any file whose location would be modified by a symbolic link is not extracted. This is, in part, achieved by ensuring that extracted directories are not symlinks. Additionally, in order to prevent unnecessary stat calls to determine whether a given path is a directory, paths are cached when directories are created.
This logic was insufficient when extracting tar files that contained both a directory and a symlink with the same name as the directory. This order of operations resulted in the directory being created and added to the node-tar directory cache. When a directory is present in the directory cache, subsequent calls to mkdir for that directory are skipped. However, this is also where node-tar checks for symlinks occur.
By first creating a directory, and then replacing that directory with a symlink, it was thus possible to bypass node-tar symlink checks on directories, essentially allowing an untrusted tar file to symlink into an arbitrary location and subsequently extracting arbitrary files into that location, thus allowing arbitrary file creation and overwrite.
This issue was addressed in releases 3.2.3, 4.4.15, 5.0.7 and 6.1.2.
Patches
3.2.3 || 4.4.15 || 5.0.7 || 6.1.2
Workarounds
Users may work around this vulnerability without upgrading by creating a custom filter method which prevents the extraction of symbolic links.
const tar = require('tar')
tar.x({
file: 'archive.tgz',
filter: (file, entry) => {
if (entry.type === 'SymbolicLink') {
return false
} else {
return true
}
}
})Users are encouraged to upgrade to the latest patch versions, rather than attempt to sanitize tar input themselves.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | tar | >= 3.0.0, < 3.2.3, >= 4.0.0, < 4.4.15, >= 5.0.0, < 5.0.7, >= 6.0.0, < 6.1.2 | 3.2.3, 4.4.15, 5.0.7, 6.1.2 |
References
- https://github.com/npm/node-tar/security/advisories/GHSA-r628-mhmh-qjhw
- https://nvd.nist.gov/vuln/detail/CVE-2021-32803
- https://github.com/isaacs/node-tar/commit/46fe35083e2676e31c4e0a81639dce6da7aaa356
- https://github.com/isaacs/node-tar/commit/5987d9a41f6bfbf1ddab1098e1fdcf1a5618f571
- https://github.com/isaacs/node-tar/commit/85d3a942b4064e4ff171f91696fced7975167349
- https://github.com/isaacs/node-tar/commit/9dbdeb6df8e9dbd96fa9e84341b9d74734be6c20
- https://github.com/npm/node-tar/commit/9dbdeb6df8e9dbd96fa9e84341b9d74734be6c20
- https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
- https://github.com/isaacs/node-tar
- https://www.npmjs.com/advisories/1771
- https://www.npmjs.com/package/tar
- https://www.oracle.com/security-alerts/cpuoct2021.html
- CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N- Weakness (CWE)
CWE-22, CWE-23, CWE-59- Platform
- npm
- Package
tar- Disclosed
- 03.08.2021
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-r628-mhmh-qjhw - CC BY 4.0
Vulnerability history: tar
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 21
- First → latest
- 10.2017 07.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 15
- Medium 5
Disclosures per year
- 2017: 1
- 2018: 0
- 2019: 1
- 2020: 0
- 2021: 5
- 2022: 0
- 2023: 0
- 2024: 1
- 2025: 1
- 2026: 12
-
Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning this entry
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