# CVE-2026-5068: Zephyr OS out-of-bounds write in Bluetooth L2CAP LE CoC

Source: https://junglewise.ai/threats/cve-2026-5068-zephyr-os-out-of-bounds-write-in-bluetooth-l2cap-le-coc  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-09. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

CVE-2026-5068 · Severity: high · CVSS 7.6 · Published 2026-06-09

A vulnerability exists in the Bluetooth software of the Zephyr operating system, which is commonly used in embedded and IoT devices. A nearby attacker can send specially crafted Bluetooth signals to cause the device to crash or malfunction. This could lead to a complete service outage or allow an attacker to corrupt the device's memory, potentially impacting its reliability and security.

Technologies: [Zephyr Project Zephyr OS](https://junglewise.ai/threats/technologies/zephyr-os). Vendors: [Zephyr Project](https://junglewise.ai/threats/vendors/zephyr-project).

## Quick answers

**Is CVE-2026-5068 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5068 being exploited in the wild.

**How severe is CVE-2026-5068?** High severity, with a CVSS score of 7.6, published 9 June 2026.

**Which products and versions are affected?** Zephyr Project Zephyr OS <= 4.4.0.

**Is there a fix for CVE-2026-5068?** 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.

**How is CVE-2026-5068 attacked?** It is attacked from the adjacent network, in an operating system.

**Am I affected by CVE-2026-5068?** Check whether you run Zephyr Project Zephyr OS 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

An out-of-bounds (OOB) write vulnerability exists in the Zephyr Bluetooth host within the L2CAP LE Credit Based Flow Control (CoC) SDU reassembly logic. The flaw is located in `l2cap_chan_le_recv_seg` in `subsys/bluetooth/host/l2cap.c`. When an application enables segmentation via `chan_ops.alloc_buf` and the RX pool's `user_data_size` is configured to be smaller than 2 bytes, the segmentation counter is written past the allocated buffer. An unauthenticated attacker within Bluetooth range (adjacent) can exploit this to cause heap corruption, a fatal error, or an AddressSanitizer abort. Patches have been developed for the main branch and version 4.3.

## Affected products

- Zephyr Project Zephyr OS <= 4.4.0

## Timeline

- 2026-05-21: other: Embargo date
- 2026-06-09: disclosed: Initial disclosure and NVD publication

## References

- [https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-qrcq-hxwj-mqxm](https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-qrcq-hxwj-mqxm)

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- [Zephyr Bluetooth Link Layer memory leak in connection update](https://junglewise.ai/threats/cve-2026-19739-the-bluetooth-link-layer-control-procedure-code-in-subsys)