---
title: "CVE-2021-37701\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2021-37701?format=md
keywords: index, follow
---

# CVE-2021-37701

Publication date 31 August 2021

Last updated 26 August 2025

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**8.2 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2021-37701?format=md#impact-score)

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## Description

The npm package "tar" (aka node-tar) before versions 4.4.16, 5.0.8, and
6.1.7 has an arbitrary file creation/overwrite and arbitrary code execution
vulnerability. 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, where the symlink and directory names in the archive entry used
backslashes as a path separator on posix systems. The cache checking logic
used both `\` and `/` characters as path separators, however `\` is a valid
filename character on posix systems. 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. Additionally, a similar confusion could arise on
case-insensitive filesystems. If a tar archive contained a directory at
`FOO`, followed by a symbolic link named `foo`, then on case-insensitive
file systems, the creation of the symbolic link would remove the directory
from the filesystem, but \_not\_ from the internal directory cache, as it
would not be treated as a cache hit. A subsequent file entry within the
`FOO` directory would then be placed in the target of the symbolic link,
thinking that the directory had already been created. These issues were
addressed in releases 4.4.16, 5.0.8 and 6.1.7. The v3 branch of node-tar
has been deprecated and did not receive patches for these issues. If you
are still using a v3 release we recommend you update to a more recent
version of node-tar. If this is not possible, a workaround is available in
the referenced GHSA-9r2w-394v-53qc.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| node-tar | 26.04 LTS resolute | Not affected |
| 25.10 questing | Not affected |
| 25.04 plucky | Not affected |
| 24.10 oracular | Not affected |
| 24.04 LTS noble | Not affected |
| 23.10 mantic | Not affected |
| 23.04 lunar | Not affected |
| 22.10 kinetic | Not affected |
| 22.04 LTS jammy | Not affected |
| 21.10 impish | Not affected |
| 21.04 hirsute | Ignored end of life |
| 20.04 LTS focal | Needs evaluation |
| 18.04 LTS bionic | Needs evaluation |
| 16.04 LTS xenial | Needs evaluation |
| 14.04 LTS trusty | Needs evaluation |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

8.2 · High

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Local |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | Required |
  | Scope | Changed |
  | Confidentiality impact | High |
  | Integrity impact | High |
  | Availability impact | None |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 8.2 · High |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-37701)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2021-37701)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2021-37701)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2021-37701)

### Other references

* <https://github.com/npm/node-tar/security/advisories/GHSA-9r2w-394v-53qc>
* <https://www.npmjs.com/package/tar>
* <https://www.cve.org/CVERecord?id=CVE-2021-37701>