---
id: CVE-2026-5068
title: 'bt: l2cap le coc: remote oob write via seg counter stored in net_buf user_data'
summary: >-
  A remote, unauthenticated BLE peer can trigger a 2-byte out-of-bounds write in
  the Bluetooth host during L2CAP LE CoC SDU reassembly. When the application
  enables segmentation (via chan_ops.alloc_buf) and the chosen RX pool has a
  user_da…
severity: high
cvss: 7.6
cvssVector: 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H'
cvssSource: cna
cwe:
  - CWE-787
vendor: zephyrproject-rtos
product: Zephyr
affected:
  - Zephyr >= 1.14.0 < 4.3.1
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-06-09T13:10:35.371642Z'
published: '2026-06-09'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T22:10:25.872Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-5068'
references:
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-qrcq-hxwj-mqxm
tags:
  - cve.org
epss: 0.00322
epssPercentile: 0.23578
ingestedAt: '2026-10-15T22:48:25.575Z'
---

## Overview

A remote, unauthenticated BLE peer can trigger a 2-byte out-of-bounds write in the Bluetooth host during L2CAP LE CoC SDU reassembly. When the application enables segmentation (via chan_ops.alloc_buf) and the chosen RX pool has a user_data_size smaller than 2 bytes, the segmentation counter stored in the net_buf user_data area is written out of bounds in l2cap_chan_le_recv_seg (subsys/bluetooth/host/l2cap.c). The observed effects are an AddressSanitizer abort and, without ASan, heap corruption / fatal error.

## Affected

- `Zephyr >= 1.14.0 < 4.3.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.