# CVE-2026-5068: bt: l2cap le coc: remote oob write via seg counter stored in net_buf user_data

> A remote attacker can cause heap corruption or code execution in Zephyr RTOS via a Bluetooth L2CAP segmentation flaw when specific buffer configurations are used.

- **Severity:** High 7.6 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Jun 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-qrcq-hxwj-mqxm

## What is CVE-2026-5068?

CVE-2026-5068 is a high-severity memory corruption vulnerability in Zephyrproject Zephyr, published on 9 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2026-5068?

It affects 1 product.


Products: Zephyrproject Zephyr.

## How do I fix CVE-2026-5068?

No fix has been published for CVE-2026-5068 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5068 being exploited?

There is no known exploitation of CVE-2026-5068 in the wild and no public exploit code.

## Other vulnerabilities in Zephyrproject Zephyr

- [CVE-2026-5067](https://insights.sbomify.com/CVE-2026-5067/): Out-of-bounds read/write in HTTP WebSocket upgrade via non-null-terminated Sec-WebSocket-Key (critical 9.8)
- [CVE-2022-3806](https://insights.sbomify.com/CVE-2022-3806/): Bluetooth HCI Error Handling Double Free (critical 9.8)
- [CVE-2017-14199](https://insights.sbomify.com/CVE-2017-14199/): Memory corruption in getaddrinfo (critical 9.8)
- [CVE-2018-1000800](https://insights.sbomify.com/CVE-2018-1000800/): Null dereference in n/a (critical 9.8)
- [CVE-2021-3329](https://insights.sbomify.com/CVE-2021-3329/): DOS: Incorrect handling of the initial HCI ACL_MTU handshake packet leads to crash of bluetooth host layer (critical 9.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5068 and fix it if it is affected.

What it is: CVE-2026-5068 is a high-severity memory corruption vulnerability in Zephyrproject Zephyr, published on 9 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-5068 in the wild and no public exploit code.

Affected product: Zephyrproject Zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-5068/ (Markdown: https://insights.sbomify.com/CVE-2026-5068/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5068
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5068
- OSV: https://osv.dev/vulnerability/CVE-2026-5068

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5068/
Summaries are generated and may contain mistakes; the official description above is the record.