# CVE-2026-74533: Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero

> A race condition in the Linux kernel Bluetooth ISO subsystem allows use-after-free, potentially enabling code execution or privilege escalation.

- **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:** 15 Aug 2026
- **Updated:** 21 Oct 2026
- **Also known as:** BELL-CVE-2026-74533, DEBIAN-CVE-2026-74533, GHSA-xf88-xmxw-hhch, UBUNTU-CVE-2026-74533

## What is CVE-2026-74533?

CVE-2026-74533 is a high-severity vulnerability in Linux, published on 15 Aug 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: fix race of kfree vs kref_get_unless_zero

hci_conn::iso_data is accessed and modified without lock or RCU.
This leads to a race

    [Task hdev->workqueue]                 	[Task 2]
    iso_recv                                    iso_conn_put(conn)
      conn = LOAD hcon->iso_data                  iso_conn_free(conn)
      iso_conn_hold_unless_zero(conn)               hcon->iso_data = NULL
                                                    kfree(conn)
        kref_get_unless_zero(&conn->ref) /* UAF */

and also to races in iso_conn_add() vs. iso_conn_free().

Fix by adding spinlock hci_conn::proto_lock and using it to guard
hci_conn::iso_data.

## Which versions are affected by CVE-2026-74533?


## How do I fix CVE-2026-74533?

Apply the vendor's patch.

## Is CVE-2026-74533 being exploited?

There is no known exploitation of CVE-2026-74533 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74533 and fix it if it is affected.

What it is: CVE-2026-74533 is a high-severity vulnerability in Linux, published on 15 Aug 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-2026-74533 in the wild and no public exploit code.

Affected product: Linux. 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-2026-74533/ (Markdown: https://insights.sbomify.com/CVE-2026-74533/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74533
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74533
- OSV: https://osv.dev/vulnerability/CVE-2026-74533

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74533/
Summaries are generated and may contain mistakes; the official description above is the record.