# CVE-2026-33243: barebox: FIT Signature Verification Bypass Vulnerability

> An attacker can bypass FIT signature verification in barebox to boot unverified images by modifying the hashed-nodes property.

- **Severity:** High 8.3 (`CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 Mar 2026
- **Updated:** 26 Mar 2026
- **Also known as:** OESA-2026-1834

## What is CVE-2026-33243?

CVE-2026-33243 is a high-severity vulnerability in barebox, published on 20 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

barebox is a bootloader. In barebox from version 2016.03.0 to before version 2026.03.1 (and the corresponding backport to 2025.09.3), an attacker could exploit a FIT signature verification vulnerability to trick the bootloader into booting different images than those that were verified as part of a signed configuration. mkimage(1) sets the hashed-nodes property of the FIT signature node to list which nodes of the FIT were hashed as part of the signing process as these will need to be verified later on by the bootloader. However, hashed-nodes itself is not part of the hash and could therefore be modified to allow booting different images than those that have been verified. This issue has been patched in barebox versions 2026.03.1 and backported to 2025.09.3.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2026-33243?

It affects 1 product.


Products: Pengutronix Barebox.

## How do I fix CVE-2026-33243?

Upgrade to a fixed version.

## Is CVE-2026-33243 being exploited?

There is no known exploitation of CVE-2026-33243 in the wild and no public exploit code.

## Other vulnerabilities in barebox

- [CVE-2019-15937](https://insights.sbomify.com/CVE-2019-15937/): Memory corruption in n/a (critical 9.8)
- [CVE-2019-15938](https://insights.sbomify.com/CVE-2019-15938/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-13910](https://insights.sbomify.com/CVE-2020-13910/): Information disclosure in n/a (critical 9.1)
- [CVE-2026-34963](https://insights.sbomify.com/CVE-2026-34963/): barebox EFI PE Loader Memory Safety Vulnerabilities (high 8.6)
- [CVE-2021-37847](https://insights.sbomify.com/CVE-2021-37847/): Information disclosure in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33243 and fix it if it is affected.

What it is: CVE-2026-33243 is a high-severity vulnerability in barebox, published on 20 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-33243 in the wild and no public exploit code.

Affected product: barebox. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-33243/ (Markdown: https://insights.sbomify.com/CVE-2026-33243/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33243
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33243
- OSV: https://osv.dev/vulnerability/CVE-2026-33243

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33243/
Summaries are generated and may contain mistakes; the official description above is the record.