# CVE-2026-88839: BusyBox passwd/group tokenize() heap pointer out-of-bounds write

Source: https://junglewise.ai/threats/cve-2026-88839-busybox-passwd-group-tokenize-references-a-stale-endpoint-pointer  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-23. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-88839 · Severity: medium · CVSS 6.7 · Published 2026-09-23

BusyBox is a lightweight utility suite commonly used in embedded systems and container images. A flaw in the passwd/group parsing code causes a stale pointer reference after string trimming, leading to an out-of-bounds heap write. An attacker with the ability to provide malformed passwd or group data could corrupt heap memory and potentially achieve code execution.

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

## Quick answers

**Is CVE-2026-88839 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88839 being exploited in the wild.

**How severe is CVE-2026-88839?** Medium severity, with a CVSS score of 6.7, published 23 September 2026.

**Which products and versions are affected?** Busybox before 1.37.0-9.1.

**Is there a fix for CVE-2026-88839?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2026-88839?** 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

The vulnerability exists in BusyBox's tokenize() function used for parsing passwd/group files, where a pointer to the end of a string is not updated after trimming operations, resulting in an out-of-bounds write. The flaw allows writing of heap pointers outside allocated bounds. This is a memory corruption vulnerability that could be triggered through crafted passwd or group file content.

## Affected products

- BusyBox BusyBox before 1.37.0-9.1

## Timeline

- 2026-09-23: disclosed
- 2026-09-25: advisory: Red Hat security advisory RHSA-2026:72111 issued

## References

- [https://catalog.redhat.com/software/containers/](https://catalog.redhat.com/software/containers/)
- [https://access.redhat.com/errata/RHSA-2026:72111](https://access.redhat.com/errata/RHSA-2026:72111)

## Related threats

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