CVE-2021-32804: Tar Arbitrary File Creation/Overwrite Due To Vulnerability

HIGH
Advisory Identifier: GHSA-3jfq-g458-7qm9
CVSS 8.2
CWE-22
Published
Advisory Summary

CVE-2021-32804 is a HIGH (CVSS 8.2) arbitrary file creation/overwrite due to vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Tar libraries in the npm ecosystem. The issue involves arbitrary file creation/overwrite due to insufficient absolute path sanitization. Remediation is available by upgrading affected packages to version 3.2.2, 4.4.14, 5.0.6, 6.1.1.

CVE-2021-32804 at a Glance

CVE Identifier CVE-2021-32804
GHSA Identifier GHSA-3jfq-g458-7qm9
Severity HIGH
CVSS v3.1 Base Score 8.2
CWE Classification CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected Product Tar
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2021-32804

To remediate this vulnerability, upgrade all affected Tar dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

tar fixed: 3.2.2
npm install tar@3.2.2
tar fixed: 4.4.14
npm install tar@4.4.14
tar fixed: 5.0.6
npm install tar@5.0.6
tar fixed: 6.1.1
npm install tar@6.1.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

npm ls tar

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2021-32804, inspect your project dependencies using npm:

npm ls tar

Analyze the terminal output to locate any version of Tar in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.2.2), your application is affected.

Note: The npm ls tar command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'), where the product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. In Tar, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Arbitrary File Creation, Arbitrary File Overwrite, Arbitrary Code Execution `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. ### Patches 3.2.2 || 4.4.14 || 5.0.6 || 6.1.1 NOTE: an adjacent issue [CVE-2021-32803](https://github.com/npm/node-tar/security/advisories/GHSA-r628-mhmh-qjhw) affects this release level. Please ensure you update to the latest patch levels that address CVE-2021-32803 as well if this adjacent issue affects your `node-tar` use case. ### Workarounds 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. ```js const path = require('path') const tar = require('tar') tar.x({ file: 'archive.tgz', // either add this function... onentry: (entry) => { if (path.isAbsolute(entry.path)) { entry.path = sanitizeAbsolutePathSomehow(entry.path) entry.absolute = path.resolve(entry.path) } }, // or this one filter: (file, entry) => { if (path.isAbsolute(entry.path)) { return false } else { return true } } }) ``` Users are encouraged to upgrade to the latest patch versions, rather than attempt to sanitize tar input themselves.

CVE-2021-32804 Affected Tar Versions

4 component(s)
Fixed Versions:
3.2.24.4.145.0.66.1.1
Product / Package Ecosystem Affected Versions Fixed Version
tar
npm
< 3.2.2
3.2.2
tar
npm
≥ 4.0.0
< 4.4.14
4.4.14
tar
npm
≥ 5.0.0
< 5.0.6
5.0.6
tar
npm
≥ 6.0.0
< 6.1.1
6.1.1

References

Frequently Asked Questions

What is CVE-2021-32804?
CVE-2021-32804 is a security vulnerability in Tar involving Arbitrary File Creation/Overwrite due to insufficient absolute path sanitization under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal').
Which Tar versions are affected?
Affected versions include releases prior to 3.2.2, 4.4.14, 5.0.6, 6.1.1 across affected packages: tar.
What version fixes CVE-2021-32804?
Upgrading to 3.2.2, 4.4.14, 5.0.6, 6.1.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tar affected?
Yes, tar is affected in releases prior to 3.2.2, 4.4.14, 5.0.6, 6.1.1. Upgrade your dependency to 3.2.2, 4.4.14, 5.0.6, 6.1.1 or later.
What is the CVSS score of CVE-2021-32804?
CVE-2021-32804 has a CVSS v3.1 base score of 8.2 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N.
What CWE is associated with CVE-2021-32804?
CVE-2021-32804 is classified under CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') (The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.).
How can I check npm dependencies for CVE-2021-32804?
Run the dependency tree command: 'npm ls tar'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-3jfq-g458-7qm9",
  "modified" : "2021-08-30T23:14:50Z",
  "published" : "2021-08-03T19:06:36Z",
  "aliases" : [ "CVE-2021-32804" ],
  "summary" : "Arbitrary File Creation/Overwrite due to insufficient absolute path sanitization",
  "details" : "### Impact\n\nArbitrary File Creation, Arbitrary File Overwrite, Arbitrary Code Execution\n\n`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`. \n\nThis 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. \n\n### Patches\n\n3.2.2 || 4.4.14 || 5.0.6 || 6.1.1\n\nNOTE: an adjacent issue [CVE-2021-32803](https://github.com/npm/node-tar/security/advisories/GHSA-r628-mhmh-qjhw) affects this release level. Please ensure you update to the latest patch levels that address CVE-2021-32803 as well if this adjacent issue affects your `node-tar` use case.\n\n### Workarounds\n\nUsers 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.\n\n```js\nconst path = require('path')\nconst tar = require('tar')\n\ntar.x({\n  file: 'archive.tgz',\n  // either add this function...\n  onentry: (entry) => {\n    if (path.isAbsolute(entry.path)) {\n      entry.path = sanitizeAbsolutePathSomehow(entry.path)\n      entry.absolute = path.resolve(entry.path)\n    }\n  },\n\n  // or this one\n  filter: (file, entry) => {\n    if (path.isAbsolute(entry.path)) {\n      return false\n    } else {\n      return true\n    }\n  }\n})\n```\n\nUsers are encouraged to upgrade to the latest patch versions, rather than attempt to sanitize tar input themselves.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N"
  } ],
  "affected" : [ {
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  }, {
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    "ranges" : [ {
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        "introduced" : "6.0.0"
      }, {
        "fixed" : "6.1.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/npm/node-tar/security/advisories/GHSA-3jfq-g458-7qm9"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-32804"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/npm/node-tar/commit/1f036ca23f64a547bdd6c79c1a44bc62e8115da4"
  }, {
    "type" : "WEB",
    "url" : "https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/npm/node-tar"
  }, {
    "type" : "WEB",
    "url" : "https://www.npmjs.com/advisories/1770"
  }, {
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  }, {
    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpuoct2021.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-03T19:06:15Z",
    "nvd_published_at" : "2021-08-03T19:15:00Z"
  }
}