Executive brief
barebox, an open-source bootloader used in embedded systems, is vulnerable to a denial-of-service attack during the boot process. By providing a specially crafted storage device or filesystem image, an attacker can cause the system to hang indefinitely during startup. This prevents the device from booting its operating system, effectively disabling the hardware.
Technical details
A denial-of-service vulnerability exists in the ext4 directory parsing logic of barebox (specifically within fs/ext4/ext4_common.c). The function ext4fs_iterate_dir() fails to validate that the directory entry length (direntlen) is non-zero. An attacker can provide a malicious ext4 filesystem image where a directory entry has a length of 0. When barebox attempts to list the directory or resolve a path during boot, it enters an infinite loop because the pointer never advances. This results in a 'Loop with Unreachable Exit Condition' (CWE-835). The issue is fixed in version 2026.04.0 by adding validation for directory entry lengths.
Affected products
- Pengutronix barebox prior to 2026.04.0
Timeline
- 2026-04-17: patched: Version 2026.04.0 released with ext4 protection fixes.
- 2026-05-11: disclosed: Initial CVE publication.