# CVE-2025-70293: Denx U-Boot integer overflow in ext4fs_get_bgdtable

Source: https://junglewise.ai/threats/cve-2025-70293-denx-u-boot-integer-overflow-in-ext4fs-get-bgdtable  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-26. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2025-70293 · Severity: critical · CVSS 9.8 · Published 2026-08-26

U-Boot is a widely-used bootloader that initializes hardware and loads the operating system on embedded devices and servers. An integer overflow in ext4 filesystem handling causes a buffer to be under-allocated, allowing an attacker to overflow the buffer during memory operations. This could lead to arbitrary code execution during the boot process, enabling device compromise, data loss, or system outage.

Technologies: [Denx U-Boot](https://junglewise.ai/threats/technologies/u-boot). Vendors: [Denx](https://junglewise.ai/threats/vendors/denx).

## Quick answers

**Is CVE-2025-70293 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2025-70293 being exploited in the wild.

**How severe is CVE-2025-70293?** Critical severity, with a CVSS score of 9.8, published 26 August 2026.

**Which products and versions are affected?** Denx U-Boot before 2026.04.

**Is there a fix for CVE-2025-70293?** A patch was published on 2026-04: Fix available in U-Boot 2026.04 and later Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2025-70293 attacked?** It is attacked over the network or with local access or with physical access.

**Am I affected by CVE-2025-70293?** Check whether you run Denx U-Boot 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

The vulnerability is an integer overflow in the ext4fs_get_bgdtable function that miscalculates buffer size, resulting in under-allocation. When the undersized buffer is subsequently used in memcpy(), a heap buffer overflow occurs. The vulnerability is reachable via a malicious ext4 filesystem image, which an attacker could present during boot (e.g., via USB, network boot, or a compromised storage device). Successful exploitation allows arbitrary code execution in the bootloader context. Patches are available in U-Boot version 2026.04 and later.

## Affected products

- Denx U-Boot before 2026.04

## Timeline

- 2026-08-26: disclosed
- 2026-04: patched: Fix available in U-Boot 2026.04 and later

## References

- [http://denx.com/](http://denx.com/)
- [http://u-boot.com/](http://u-boot.com/)

## Related threats

- [Denx U-Boot integer overflow in ZFS filesystem support](https://junglewise.ai/threats/cve-2025-70290-denx-u-boot-integer-overflow-in-zfs-filesystem-support)
- [Improper access control for volatile memory containing boot code in Universal Boot Loader (U-Boot) before 2017.11 and…](https://junglewise.ai/threats/cve-2025-24857-improper-access-control-for-volatile-memory-containing-boot-code)
- [Das U-Boot integer overflows in memory allocator](https://junglewise.ai/threats/cve-2024-57258-das-u-boot-integer-overflows-in-memory-allocator)
- [Das U-Boot integer overflow in ext4fs_read_symlink](https://junglewise.ai/threats/cve-2024-57256-das-u-boot-integer-overflow-in-ext4fs-read-symlink)
- [DENX U-Boot heap buffer overflow in USB DFU implementation](https://junglewise.ai/threats/cve-2022-2347-denx-u-boot-heap-buffer-overflow-in-usb-dfu-implementation)