Executive brief
barebox is an open-source bootloader used to initialize hardware and start the operating system on embedded devices like industrial controllers and automotive systems. A vulnerability in how it handles ext4 filesystems could allow an attacker with physical access to the device (via USB or SD card) or control over the local boot network to crash the system during startup. This could lead to a denial-of-service state where the device fails to boot correctly, potentially impacting operations or requiring manual recovery.
Technical details
An out-of-bounds read vulnerability (CWE-125) exists in the barebox bootloader's ext4 filesystem implementation. The flaw is located in 'fs/ext4/ext4_common.c' where the 'eh_entries' field, which specifies the number of entries in an extent header, is used as a loop bound without being validated against the actual buffer capacity. An attacker can exploit this by providing a specially crafted ext4 filesystem image via physical media (USB/SD card) or network boot (PXE). During boot-time parsing, the lack of bounds checking causes the pointer to advance beyond the allocated heap buffer, leading to information leaks or a system crash (Denial of Service). The issue is resolved in version 2026.04.0.
Affected products
- Pengutronix barebox versions prior to 2026.04.0
Timeline
- 2026-04-17: patched: Version 2026.04.0 released with fixes for ext4 parsing.
- 2026-05-11: disclosed: Initial CVE publication.