tar-rs unpack_in can chmod arbitrary directories by following symlinks

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.1 · 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 · score source

EPSS

• CVE-2026-33056: 0.39% estimated exploitation activity in the next 30 days; percentile 32.68 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When unpacking a tar archive, the tar crate's unpackdir 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, createdir("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…

Published by the source

20 Mar 2026, 17:25 UTC

Last modified by the source

25 Mar 2026, 18:36 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-j4xf-2g29-59ph

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# Patch Next advisory brief: CVE-2026-33056

Advisory: tar-rs `unpack_in` can chmod arbitrary directories by following symlinks
IDs: CVE-2026-33056, GHSA-j4xf-2g29-59ph
Record: https://patchnext.com/advisories/cve-2026-33056 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tar 0.4.45. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io tar: affected <= 0.4.44; fixed in 0.4.45

## Suggested inspection (read-only)
- crates.io tar: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on tar.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-j4xf-2g29-59ph (GitHub-reviewed advisory GHSA-j4xf-2g29-59ph lists affected ranges: crates.io tar >=0 <=0.4.44)

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