# CVE-2026-74537: Bluetooth: ISO: hold sk properly in iso_conn_ready

> A race condition in the Linux kernel Bluetooth ISO subsystem allows a use-after-free, potentially enabling local attackers to execute code or escalate privileges.

- **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-2026-74537, DEBIAN-CVE-2026-74537, GHSA-4f56-g5vg-w2cg, UBUNTU-CVE-2026-74537

## What is CVE-2026-74537?

CVE-2026-74537 is a high-severity use after free 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: hold sk properly in iso_conn_ready

sk deref in iso_conn_ready must be done either under conn->lock, or
holding a refcount, to avoid concurrent close. conn->sk is currently
accessed without either:

    [Task 1]            [Task 2]
                        iso_sock_release
    iso_conn_ready
      sk = conn->sk
                          lock_sock(sk)
                            conn->sk = NULL
      lock_sock(sk)
                          release_sock(sk)
                          iso_sock_kill(sk)
       UAF on sk deref

Fix possible UAF by holding sk refcount in iso_conn_ready().  Also
recheck after lock_sock that the socket is still valid.  Adjust locking
so conn->sk is cleared only under lock_sock.

## Which versions are affected by CVE-2026-74537?


## How do I fix CVE-2026-74537?

Apply the vendor's patch.

## Is CVE-2026-74537 being exploited?

There is no known exploitation of CVE-2026-74537 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74537 and fix it if it is affected.

What it is: CVE-2026-74537 is a high-severity use after free 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-2026-74537 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-2026-74537/ (Markdown: https://insights.sbomify.com/CVE-2026-74537/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74537
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74537
- OSV: https://osv.dev/vulnerability/CVE-2026-74537

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74537/
Summaries are generated and may contain mistakes; the official description above is the record.