# CVE-2026-90254: Bluetooth: hci_sync: free the advertising instance on the failure and cancel paths

> A memory leak in the Linux kernel Bluetooth subsystem allows attackers to cause denial of service by triggering specific failure or cancellation paths in advertising instances.

- **Severity:** Not scored
- **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:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-102884, BELL-CVE-2026-90254, DEBIAN-CVE-2026-90254, GHSA-cq3p-99wv-3cqf, UBUNTU-CVE-2026-90254

## What is CVE-2026-90254?

CVE-2026-90254 is a memory corruption vulnerability in Linux, published on 17 Sep 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: hci_sync: free the advertising instance on the failure and cancel paths

adv_timeout_expire() hands a kmalloc()ed instance byte to
hci_cmd_sync_queue() with a NULL destroy callback, and only
adv_timeout_expire_sync() frees it. That leaks on two paths:

 - the return value is not checked, and hci_cmd_sync_queue() does not
   take ownership when it fails (-ENETDOWN, -ENODEV, -ENOMEM);

 - a cancelled entry is not released, as _hci_cmd_sync_cancel_entry()
   does not free entry->data when there is no destroy callback.
   hci_cmd_sync_clear() cancels every pending entry when the controller
   is unregistered.

Free the buffer from a destroy callback, and in the caller when the entry
could not be queued at all.

## Which versions are affected by CVE-2026-90254?


## How do I fix CVE-2026-90254?

Apply the vendor's patch.

## Is CVE-2026-90254 being exploited?

There is no known exploitation of CVE-2026-90254 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90254 and fix it if it is affected.

What it is: CVE-2026-90254 is a memory corruption vulnerability in Linux, published on 17 Sep 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-2026-90254 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-2026-90254/ (Markdown: https://insights.sbomify.com/CVE-2026-90254/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90254
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90254
- OSV: https://osv.dev/vulnerability/CVE-2026-90254

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90254/
Summaries are generated and may contain mistakes; the official description above is the record.