CVE-2026-33056: Tar Tar-rs `unpack_in` Can Chmod Arbitrary Vulnerability

MODERATE
Advisory Identifier: GHSA-j4xf-2g29-59ph
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CVSS 6.5
CWE-61
Published
Advisory Summary

CVE-2026-33056 is a MODERATE (CVSS 6.5) tar-rs `unpack_in` can chmod arbitrary vulnerability (CWE-61: UNIX Symbolic Link (Symlink) Following) affecting Tar libraries in the crates.io ecosystem. The issue involves tar-rs `unpack_in` can chmod arbitrary directories by following symlinks. Remediation is available by upgrading affected packages to version 0.4.45.

CVE-2026-33056 at a Glance

CVE Identifier CVE-2026-33056
GHSA Identifier GHSA-j4xf-2g29-59ph
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-61: UNIX Symbolic Link (Symlink) Following
Affected Product Tar
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 6.5

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:R/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 Required (UI:R)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity High (I:H)
Availability None (A:N)

How to Fix CVE-2026-33056

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: 0.4.45 
Upgrade tar to 0.4.45
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-2026-33056, 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 0.4.45), 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-61: UNIX Symbolic Link (Symlink) Following, where the product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. this could allow an attacker to cause the product to operate on unauthorized files. 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

## Summary When unpacking a tar archive, the `tar` crate's `unpack_dir` function uses `fs::metadata()` to check whether a path that already exists is a directory. Because `fs::metadata()` follows symbolic links, a crafted tarball containing a symlink entry followed by a directory entry with the same name causes the crate to treat the symlink target as a valid existing directory — and subsequently apply `chmod` to it. This allows an attacker to modify the permissions of arbitrary directories outside the extraction root. ## Reproducer A malicious tarball contains two entries: (1) a symlink `foo` pointing to an arbitrary external directory, and (2) a directory entry `foo/.` (or just `foo`). When unpacked, `create_dir("foo")` fails with `EEXIST` because the symlink is already on disk. The `fs::metadata()` check then follows the symlink, sees a directory at the target, and allows processing to continue. The directory entry's mode bits are then applied via `chmod`, which also follows the symlink — modifying the permissions of the external target directory. ## Fix The fix is very simple, we now use `fs::symlink_metadata()` in `unpack_dir`, so symlinks are detected and rejected rather than followed. ## Credit This issue was reported by @xokdvium - thank you!

CVE-2026-33056 Affected Tar Versions

1 component(s)
Fixed Versions:
0.4.45
Product / Package Ecosystem Affected Versions Fixed Version
tar
 crates.io
< 0.4.45
0.4.45

References

GitHub Advisory / Wiki ADVISORY
https://github.com/alexcrichton/tar-rs/security/advisories/GHSA-j4xf-2g29-59ph
NVD — CVE-2026-33056 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33056
Security Fix Commit FIX COMMIT
https://github.com/alexcrichton/tar-rs/commit/17b1fd84e632071cb8eef9d3709bf347bd266446
Tar Source Repository REPOSITORY
https://github.com/alexcrichton/tar-rs
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2026-0067.html

Frequently Asked Questions

What is CVE-2026-33056?
CVE-2026-33056 is a security vulnerability in Tar involving tar-rs `unpack_in` can chmod arbitrary directories by following symlinks under CWE-61: UNIX Symbolic Link (Symlink) Following.
Which Tar versions are affected?
Affected versions include releases prior to 0.4.45 across affected packages: tar.
What version fixes CVE-2026-33056?
Upgrading to 0.4.45 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tar affected?
Yes, tar is affected in releases prior to 0.4.45. Upgrade your dependency to 0.4.45 or later.
What is the CVSS score of CVE-2026-33056?
CVE-2026-33056 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N.
What CWE is associated with CVE-2026-33056?
CVE-2026-33056 is classified under CWE-61: UNIX Symbolic Link (Symlink) Following (The product, when opening a file or directory, does not sufficiently account for when the file is a symbolic link that resolves to a target outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files.).
How can I check crates.io dependencies for CVE-2026-33056?
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-j4xf-2g29-59ph",
  "modified" : "2026-03-25T18:36:33Z",
  "published" : "2026-03-20T17:25:09Z",
  "aliases" : [ "CVE-2026-33056" ],
  "summary" : "tar-rs `unpack_in` can chmod arbitrary directories by following symlinks",
  "details" : "## Summary\n\nWhen unpacking a tar archive, the `tar` crate's `unpack_dir` function uses `fs::metadata()` to check whether a path that already exists is a directory. Because `fs::metadata()` follows symbolic links, a crafted tarball containing a symlink entry followed by a directory entry with the same name causes the crate to treat the symlink target as a valid existing directory — and subsequently apply `chmod` to it. This allows an attacker to modify the permissions of arbitrary directories outside the extraction root.\n\n## Reproducer\n\nA malicious tarball contains two entries: (1) a symlink `foo` pointing to an arbitrary external directory, and (2) a directory entry `foo/.` (or just `foo`). When unpacked, `create_dir(\"foo\")` fails with `EEXIST` because the symlink is already on disk. The `fs::metadata()` check then follows the symlink, sees a directory at the target, and allows processing to continue. The directory entry's mode bits are then applied via `chmod`, which also follows the symlink — modifying the permissions of the external target directory.\n\n## Fix \n\nThe fix is very simple, we now use `fs::symlink_metadata()` in `unpack_dir`, so symlinks are detected and rejected rather than followed.\n\n## Credit\n\nThis issue was reported by @xokdvium - thank you!",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "tar"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.4.45"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.4.44"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/alexcrichton/tar-rs/security/advisories/GHSA-j4xf-2g29-59ph"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33056"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/alexcrichton/tar-rs/commit/17b1fd84e632071cb8eef9d3709bf347bd266446"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/alexcrichton/tar-rs"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2026-0067.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-61" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-20T17:25:09Z",
    "nvd_published_at" : "2026-03-20T08:16:11Z"
  }
}