# CVE-2026-63945: Bluetooth: ISO: serialize iso_sock_clear_timer with socket lock

> A race condition in the Linux kernel Bluetooth ISO subsystem allows attackers to cause a use-after-free or null dereference, potentially leading to system crashes or code execution.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-63945, DEBIAN-CVE-2026-63945, GHSA-85m8-5mhx-q797, UBUNTU-CVE-2026-63945

## What is CVE-2026-63945?

CVE-2026-63945 is a high-severity vulnerability in Linux kernel, published on 19 Jul 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: ISO: serialize iso_sock_clear_timer with socket lock

iso_sock_close() calls iso_sock_clear_timer() before acquiring
lock_sock(sk).

iso_sock_clear_timer() reads iso_pi(sk)->conn twice without the
socket lock held:

    if (!iso_pi(sk)->conn)
        return;
    cancel_delayed_work(&iso_pi(sk)->conn->timeout_work);

Concurrently, iso_conn_del() executes under lock_sock(sk) and calls
iso_chan_del(), which sets iso_pi(sk)->conn to NULL and may result in
the final reference to the connection being dropped:

    CPU0                         CPU1
    ----                         ----
    iso_sock_clear_timer()
      if (conn != NULL) ...      lock_sock(sk)
                                   iso_chan_del()
                                   iso_pi(sk)->conn = NULL
      cancel_delayed_work(conn)  /* NULL deref or UAF */

iso_pi(sk)->conn is not stable across the unlock window, causing a
NULL pointer dereference or use-after-free.

Serialize iso_sock_clear_timer() with the socket lock by moving it
inside lock_sock()/release_sock(), matching the pattern used in
iso_conn_del() and all other call sites.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-63945?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-63945?

Apply the vendor's patch.

## Is CVE-2026-63945 being exploited?

There is no known exploitation of CVE-2026-63945 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-2026-63945 and fix it if it is affected.

What it is: CVE-2026-63945 is a high-severity vulnerability in Linux kernel, published on 19 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-2026-63945 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-2026-63945/ (Markdown: https://insights.sbomify.com/CVE-2026-63945/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63945
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63945
- OSV: https://osv.dev/vulnerability/CVE-2026-63945

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63945/
Summaries are generated and may contain mistakes; the official description above is the record.