# CVE-2026-38754: BusyBox ash heap overflow in ifsbreakup

Source: https://junglewise.ai/threats/cve-2026-38754-busybox-ash-heap-overflow-in-ifsbreakup  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-15. Updated: 2026-07-15  
License: CC BY 4.0 with a link back

CVE-2026-38754 · Severity: info · CVSS 0 · Published 2026-07-15

BusyBox is a software suite that provides several Unix utilities in a single executable, commonly used in embedded systems and Linux distributions. A vulnerability in its command shell component (ash) could allow a local user to crash the shell by providing specially crafted input. This results in a denial-of-service, potentially disrupting system operations or scripts that rely on the shell.

Technologies: [Busybox](https://junglewise.ai/threats/technologies/busybox). Vendors: [Busybox](https://junglewise.ai/threats/vendors/busybox).

## Quick answers

**Is CVE-2026-38754 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-38754 being exploited in the wild.

**How severe is CVE-2026-38754?** Informational severity, with a CVSS score of 0, published 15 July 2026.

**Which products and versions are affected?** Busybox 1.38.0.

**Is there a fix for CVE-2026-38754?** A patch was published on 2026-06-16: Patch submitted to BusyBox mailing list Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-38754 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-38754?** Check whether you run Busybox 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 vulnerability exists in the ash shell component of BusyBox v1.38.0 within the ifsbreakup() function in shell/ash.c. The issue stems from the function skipping over control characters (CTLESC) without verifying if the subsequent byte remains within the bounds of the recorded memory region. If a CTLESC character is the final byte in a region, the pointer increments past the allocated buffer, leading to an out-of-bounds read or heap overflow. Additionally, the function may use stale region data after error unwinding. An attacker can exploit this by providing crafted input to the shell, leading to a crash (DoS). A patch has been proposed to cap scans to the current stack block and validate bounds during character processing.

## Affected products

- BusyBox BusyBox 1.38.0

## Timeline

- 2026-06-16: patched: Patch submitted to BusyBox mailing list
- 2026-07-15: disclosed: CVE published to NVD

## References

- [https://busybox.com/](https://busybox.com/)
- [https://lists.busybox.net/pipermail/busybox/2026-June/092353.html](https://lists.busybox.net/pipermail/busybox/2026-June/092353.html)

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