CVE-2026-33056

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.

Credit

This issue was reported by @xokdvium - thank you!

CVE-2026-33056 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.4.45); upgrading removes the vulnerable code path.

Kodem intelligence

The fix is very simple, we now use fs::symlink_metadata() in unpack_dir, so symlinks are detected and rejected rather than followed.

1. What is CVE-2026-33056? CVE-2026-33056 is a medium-severity security vulnerability in tar (rust), affecting versions <= 0.4.44. It is fixed in 0.4.45.
2. How severe is CVE-2026-33056? CVE-2026-33056 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of tar are affected by CVE-2026-33056? tar (rust) versions <= 0.4.44 is affected.
4. Is there a fix for CVE-2026-33056? Yes. CVE-2026-33056 is fixed in 0.4.45. Upgrade to this version or later.
5. Is CVE-2026-33056 exploitable, and should I be worried? Whether CVE-2026-33056 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-33056 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-33056? Upgrade tar to 0.4.45 or later.