# CVE-2026-38753: BusyBox AWK use-after-free in awk_sub

Source: https://junglewise.ai/threats/cve-2026-38753-busybox-awk-use-after-free-in-awk-sub  
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-2026-38753 · Severity: info · Published 2026-07-15

BusyBox is a software suite that provides several Unix utilities in a single executable file, commonly used in embedded systems and Linux distributions. A flaw in its text-processing tool, AWK, could allow an attacker to crash the utility by providing a specially crafted script. This results in a denial-of-service, potentially disrupting automated system tasks or administrative operations that rely on AWK.

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

## Quick answers

**Is CVE-2026-38753 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-38753 being exploited in the wild.

**How severe is CVE-2026-38753?** Informational severity, published 15 July 2026.

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

**Is there a fix for CVE-2026-38753?** A patch was published on 2026-06-16: Patch submitted to BusyBox mailing list by Sanghyun Park Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-38753 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-38753?** 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 use-after-free (UAF) vulnerability exists in the awk_sub() function within editors/awk.c of BusyBox v1.38.0. The function receives a pointer to replacement text stored in AWK variable storage; however, evaluating the regular expression argument via as_regex() can trigger a reallocation or change in that storage, leaving the replacement pointer dangling. Subsequent calls to strlen() or the replacement loop then access this freed memory. An attacker who can provide a crafted AWK script to be executed by the vulnerable BusyBox binary can trigger a crash (Denial of Service). A patch has been proposed to copy the replacement string into stable storage before the regex evaluation occurs.

## Affected products

- BusyBox BusyBox 1.38.0

## Timeline

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

## References

- [http://busybox.com/](http://busybox.com/)
- [https://lists.busybox.net/pipermail/busybox/2026-June/092352.html](https://lists.busybox.net/pipermail/busybox/2026-June/092352.html)

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