# CVE-2026-34962: barebox infinite loop in ext4 directory parsing

Source: https://junglewise.ai/threats/cve-2026-34962-barebox-infinite-loop-in-ext4-directory-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-11. Updated: 2026-07-18  
License: CC BY 4.0 with a link back

CVE-2026-34962 · Severity: medium · CVSS 6.2 · Published 2026-05-11

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.

Technologies: [Barebox](https://junglewise.ai/threats/technologies/barebox). Vendors: [Barebox](https://junglewise.ai/threats/vendors/barebox).

## Quick answers

**Is CVE-2026-34962 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34962 being exploited in the wild.

**How severe is CVE-2026-34962?** Medium severity, with a CVSS score of 6.2, published 11 May 2026.

**Which products and versions are affected?** Barebox prior to 2026.04.0.

**Is there a fix for CVE-2026-34962?** A patch was published on 2026-04-17: Version 2026.04.0 released with ext4 protection fixes. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-34962 attacked?** It is attacked with local access, in device firmware.

**Am I affected by CVE-2026-34962?** Check whether you run Barebox at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## 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.

## References

- [https://github.com/barebox/barebox](https://github.com/barebox/barebox)
- [https://github.com/barebox/barebox/releases/tag/v2026.04.0](https://github.com/barebox/barebox/releases/tag/v2026.04.0)
- [https://www.vulncheck.com/advisories/barebox-ext4-directory-parsing-infinite-loop-denial-of-service](https://www.vulncheck.com/advisories/barebox-ext4-directory-parsing-infinite-loop-denial-of-service)
- [https://y637f9qq2x.com/posts/barebox-sandbox-vulns/](https://y637f9qq2x.com/posts/barebox-sandbox-vulns/)

## Related threats

- [Das U-Boot and Barebox FIT signature verification bypass](https://junglewise.ai/threats/cve-2026-46728-das-u-boot-and-barebox-fit-signature-verification-bypass)
- [barebox integer overflow and heap overflow in EFI PE loader](https://junglewise.ai/threats/cve-2026-34963-barebox-integer-overflow-and-heap-overflow-in-efi-pe-loader)
- [barebox out-of-bounds read in ext4 extent parsing](https://junglewise.ai/threats/cve-2026-34961-barebox-out-of-bounds-read-in-ext4-extent-parsing)
- [barebox out-of-bounds read in DHCP option parsing](https://junglewise.ai/threats/cve-2026-34960-barebox-out-of-bounds-read-in-dhcp-option-parsing)
- [barebox FIT signature verification bypass](https://junglewise.ai/threats/cve-2026-33243-barebox-fit-signature-verification-bypass)