CVE-2021-38511: Tar Links Vulnerability

HIGH
Advisory Identifier: GHSA-62jx-8vmh-4mcw
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CVSS 7.5
CWE-22
Published
Advisory Summary

CVE-2021-38511 is a HIGH (CVSS 7.5) links vulnerability (CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')) affecting Tar libraries in the crates.io ecosystem. The issue involves links in archive can create arbitrary directories. Remediation is available by upgrading affected packages to version 0.4.36.

CVE-2021-38511 at a Glance

CVE Identifier CVE-2021-38511
GHSA Identifier GHSA-62jx-8vmh-4mcw
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Affected Product Tar
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 7.5

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

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

How to Fix CVE-2021-38511

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: 0.4.36 
Upgrade tar to 0.4.36
Verify Direct and Transitive Dependencies

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

inspect dependencies for tar

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-38511, inspect your project dependencies for Tar:

inspect dependencies for 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 0.4.36), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

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

When unpacking a tarball that contains a symlink the tar crate may create directories outside of the directory it's supposed to unpack into. The function errors when it's trying to create a file, but the folders are already created at this point.

CVE-2021-38511 Affected Tar Versions

1 component(s)
Fixed Versions:
0.4.36
Product / Package Ecosystem Affected Versions Fixed Version
tar
 crates.io
< 0.4.36
0.4.36

References

NVD — CVE-2021-38511 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-38511
Tar Source Repository REPOSITORY
https://github.com/alexcrichton/tar-rs/issues/238
Tar Source Repository REPOSITORY
https://github.com/alexcrichton/tar-rs/pull/259
Tar Source Repository REPOSITORY
https://github.com/alexcrichton/tar-rs
raw.githubusercontent.com/rustsec/advisory-db... WEB
https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/tar/RUSTSEC-2021-0080.md
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2021-0080.html

Frequently Asked Questions

What is CVE-2021-38511?
CVE-2021-38511 is a security vulnerability in Tar involving Links in archive can create arbitrary directories 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 0.4.36 across affected packages: tar.
What version fixes CVE-2021-38511?
Upgrading to 0.4.36 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tar affected?
Yes, tar is affected in releases prior to 0.4.36. Upgrade your dependency to 0.4.36 or later.
What is the CVSS score of CVE-2021-38511?
CVE-2021-38511 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2021-38511?
CVE-2021-38511 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 crates.io dependencies for CVE-2021-38511?
Run the dependency tree command: 'inspect dependencies for 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
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-62jx-8vmh-4mcw",
  "modified" : "2023-06-13T22:04:07Z",
  "published" : "2021-08-25T20:58:23Z",
  "aliases" : [ "CVE-2021-38511" ],
  "summary" : "Links in archive can create arbitrary directories",
  "details" : "When unpacking a tarball that contains a symlink the tar crate may create directories outside of the directory it's supposed to unpack into. The function errors when it's trying to create a file, but the folders are already created at this point.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "tar"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.4.36"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-38511"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/alexcrichton/tar-rs/issues/238"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/alexcrichton/tar-rs/pull/259"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/alexcrichton/tar-rs"
  }, {
    "type" : "WEB",
    "url" : "https://raw.githubusercontent.com/rustsec/advisory-db/main/crates/tar/RUSTSEC-2021-0080.md"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2021-0080.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-08-18T20:08:23Z",
    "nvd_published_at" : "2021-08-10T23:15:00Z"
  }
}