# CVE-2026-33055: tar-rs incorrectly ignores PAX size headers if header size is nonzero

> Attackers can craft tar archives that appear differently to tar-rs than other parsers, potentially bypassing security checks or causing logic errors.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 20 Mar 2026
- **Updated:** 20 Mar 2026
- **Also known as:** AZL-80318, AZL-80496, AZL-80505, AZL-80508, AZL-80520, AZL-83034, BELL-CVE-2026-33055, CLEANSTART-2026-MZ75626, DEBIAN-CVE-2026-33055, GHSA-gchp-q4r4-x4ff, MINI-4rgx-8qwg-8qmc, MINI-969q-m726-w87x, MINI-mx3h-cr27-vwff, MINI-wp44-j3m8-4943, RUSTSEC-2026-0068, UBUNTU-CVE-2026-33055

## What is CVE-2026-33055?

CVE-2026-33055 is a medium-severity vulnerability in alexcrichton tar-rs, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

tar-rs is a tar archive reading/writing library for Rust. Versions 0.4.44 and below have conditional logic that skips the PAX size header in cases where the base header size is nonzero. As part of CVE-2025-62518, the astral-tokio-tar project was changed to correctly honor PAX size headers in the case where it was different from the base header. This is almost the inverse of the astral-tokio-tar issue. Any discrepancy in how tar parsers honor file size can be used to create archives that appear differently when unpacked by different archivers. In this case, the tar-rs (Rust tar) crate is an outlier in checking for the header size - other tar parsers (including e.g. Go archive/tar) unconditionally use the PAX size override. This can affect anything that uses the tar crate to parse archives and expects to have a consistent view with other parsers. This issue has been fixed in version 0.4.45.

Weakness: CWE-843 (Access of Resource Using Incompatible Type)

## Which versions are affected by CVE-2026-33055?

3 open source packages ship an affected version, including tar. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `tar` | crates.io | All versions | 0.4.45 |
| `tar` | crates.io | All versions | 0.4.45 |
| `tar` | crates.io | From 0.0.0-0 | 0.4.45 |

Products: Alexcrichton Tar-Rs.

## How do I fix CVE-2026-33055?

Upgrade tar to 0.4.45 or later.

## Is CVE-2026-33055 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33055 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33055 and fix it if it is affected.

What it is: CVE-2026-33055 is a medium-severity vulnerability in alexcrichton tar-rs, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33055 exists.

Affected packages and fixed versions:
- tar (crates.io): affected all versions; fixed in 0.4.45
- tar (crates.io): affected all versions; fixed in 0.4.45
- tar (crates.io): affected from 0.0.0-0; fixed in 0.4.45

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-33055/ (Markdown: https://insights.sbomify.com/CVE-2026-33055/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33055
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33055
- OSV: https://osv.dev/vulnerability/CVE-2026-33055

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33055/
Summaries are generated and may contain mistakes; the official description above is the record.