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

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-03-20 · updated 2026-09-11
Weakness: CWE-345

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.

Affected products

barebox: from 2016.03.0 before 2025.09.3; from 2025.10.0 before 2026.03.1 — fixed in 2025.09.3, 2026.03.1

How to fix

Upgrade to a fixed version: barebox 2025.09.3, 2026.03.1. Check the vendor advisory for mitigations.

References

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