# CVE-2026-10680: Out-of-bounds access in Zephyr BR/EDR L2CAP configuration request handling via `uint16_t` length underflow

> An unauthenticated attacker within radio range can trigger an integer underflow leading to out-of-bounds memory access and potential code execution or device crash in Zephyr RTOS.

- **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:** 21 Jul 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-vrwx-p97q-8854

## What is CVE-2026-10680?

CVE-2026-10680 is a high-severity memory corruption vulnerability in Zephyrproject Zephyr, published on 21 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The Classic (BR/EDR) L2CAP signaling handlers l2cap_br_conf_req() and l2cap_br_conf_rsp() in subsys/bluetooth/host/classic/l2cap_br.c validated the minimum command size against buf->len (the bytes remaining in the whole received PDU) instead of len (the per-command data length from the L2CAP signaling header). Because multiple signaling commands can be packed into one PDU, buf->len may exceed a command's len. An attacker can send a CONF_REQ command with a header length smaller than the configuration-request structure (e.g. 0), followed by another command so that buf->len still satisfies the check. The check then passes incorrectly and opt_len = len - sizeof(*req) underflows the uint16_t to a near-0xFFFF value. The configuration-option loop, which lacks an opt_len-versus-buf->len guard, then walks far past the end of the pooled ACL receive buffer using net_buf pull primitives that perform no runtime bounds check, producing an out-of-bounds read of host memory and, when the out-of-bounds option bytes encode an MTU or flush-timeout option, an out-of-bounds write. The BR/EDR signaling channel is processed before pairing/encryption and an L2CAP channel to an L0 service such as SDP can be opened without pairing, so an unauthenticated peer within radio range that can establish an ACL connection can trigger the flaw, leading to memory corruption and denial of service (host/device crash). The defect is present in released versions including v4.4.0. The fix validates against len instead of buf->len in both handlers.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-10680?

It affects 1 product.


Products: Zephyrproject Zephyr.

## How do I fix CVE-2026-10680?

No fix has been published for CVE-2026-10680 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-10680 being exploited?

There is no known exploitation of CVE-2026-10680 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-2026-10680 and fix it if it is affected.

What it is: CVE-2026-10680 is a high-severity memory corruption vulnerability in Zephyrproject Zephyr, published on 21 Jul 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-2026-10680 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-2026-10680/ (Markdown: https://insights.sbomify.com/CVE-2026-10680/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10680
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10680
- OSV: https://osv.dev/vulnerability/CVE-2026-10680

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10680/
Summaries are generated and may contain mistakes; the official description above is the record.