# CVE-2026-43334: Bluetooth: SMP: force responder MITM requirements before building the pairing response

> An attacker can bypass Bluetooth Secure Simple Pairing MITM protections by manipulating authentication requirements during the pairing process.

- **Severity:** High 8.8 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** Yes
- **Published:** 8 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-43334, DEBIAN-CVE-2026-43334, GHSA-3ggx-x2j4-gfqr, ROOT-OS-DEBIAN-11-CVE-2026-43334, ROOT-OS-UBUNTU-2204-CVE-2026-43334, ROOT-OS-UBUNTU-2404-CVE-2026-43334, UBUNTU-CVE-2026-43334

## What is CVE-2026-43334?

CVE-2026-43334 is a high-severity vulnerability in Linux kernel, published on 8 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: SMP: force responder MITM requirements before building the pairing response

smp_cmd_pairing_req() currently builds the pairing response from the
initiator auth_req before enforcing the local BT_SECURITY_HIGH
requirement. If the initiator omits SMP_AUTH_MITM, the response can
also omit it even though the local side still requires MITM.

tk_request() then sees an auth value without SMP_AUTH_MITM and may
select JUST_CFM, making method selection inconsistent with the pairing
policy the responder already enforces.

When the local side requires HIGH security, first verify that MITM can
be achieved from the IO capabilities and then force SMP_AUTH_MITM in the
response in both rsp.auth_req and auth. This keeps the responder auth bits
and later method selection aligned.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-43334?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-43334?

Apply the vendor's patch.

## Is CVE-2026-43334 being exploited?

There is no known exploitation of CVE-2026-43334 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43334 and fix it if it is affected.

What it is: CVE-2026-43334 is a high-severity vulnerability in Linux kernel, published on 8 May 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-2026-43334 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-43334/ (Markdown: https://insights.sbomify.com/CVE-2026-43334/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43334
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43334
- OSV: https://osv.dev/vulnerability/CVE-2026-43334

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43334/
Summaries are generated and may contain mistakes; the official description above is the record.