CVE-2026-34962 in Barebox
Summary
by MITRE • 05/12/2026
barebox version prior to 2026.04.0 contains a denial-of-service vulnerability in ext4 directory parsing in fs/ext4/ext4_common.c where the ext4fs_iterate_dir() function fails to validate that directory entry length values are non-zero. Attackers can supply a malicious ext4 filesystem image with a crafted directory entry containing a direntlen value of 0 to cause an infinite loop during directory listing or path resolution, resulting in the boot process hanging indefinitely.
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Analysis
by VulDB Data Team • 07/18/2026
The vulnerability under consideration affects barebox versions prior to 2026.04.0 and resides within the ext4 filesystem implementation specifically in the fs/ext4/ext4_common.c file. This issue manifests as a denial-of-service condition that occurs during directory parsing operations, demonstrating a critical flaw in input validation mechanisms. The problem is rooted in the ext4fs_iterate_dir() function which fails to properly validate directory entry length values, creating a scenario where malformed directory entries can trigger unexpected behavior in the filesystem driver.
The technical flaw represents a classic case of insufficient input validation where the function does not check that directory entry length values remain non-zero during iteration processes. When an attacker constructs a malicious ext4 filesystem image containing a directory entry with a direntlen value of zero, the parsing logic enters an infinite loop condition. This occurs because the directory iteration routine relies on valid length values to determine when to advance to the next directory entry, and a zero-length entry causes the iteration logic to never progress properly. The vulnerability is particularly dangerous in embedded systems where barebox serves as the primary boot firmware, as it can completely halt system initialization and prevent normal operation.
The operational impact of this vulnerability extends beyond simple system unresponsiveness, as it can effectively render devices unusable during the boot process. Systems relying on barebox for initialization and boot sequence management become vulnerable to complete denial-of-service conditions that can only be resolved through physical intervention or forced system reset. This affects a wide range of embedded devices including network appliances, industrial control systems, and IoT devices where barebox is used as the firmware layer. The vulnerability is particularly concerning in environments where automated boot processes or remote management systems depend on successful filesystem access, as it can cause cascading failures in system availability.
From a cybersecurity perspective, this vulnerability aligns with CWE-129 and CWE-131 categories related to insufficient validation of length values and improper handling of buffer sizes. The attack vector can be classified under ATT&CK technique T1499.001 which covers network denial of service attacks, though in this case the attack is more specifically a local file system-based denial-of-service. The vulnerability can be exploited through manipulation of filesystem images that are subsequently mounted by the affected barebox firmware, making it particularly dangerous in scenarios where external storage media or network boot sources are used. Mitigation strategies should include immediate upgrade to barebox 2026.04.0 or later versions that contain the patched ext4 directory parsing logic, along with implementing filesystem integrity checks and monitoring for anomalous directory entry patterns in deployed systems.