# CVE-2026-72403: ALSA: FCP: Fix NULL pointer dereference in interface lookup

> A malformed USB device can trigger a NULL pointer dereference in the Linux kernel ALSA FCP driver, causing a system crash.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-72403, DEBIAN-CVE-2026-72403, GHSA-fr6v-fcwq-3cgm, UBUNTU-CVE-2026-72403

## What is CVE-2026-72403?

CVE-2026-72403 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

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

ALSA: FCP: Fix NULL pointer dereference in interface lookup

A malformed USB device can provide a vendor-specific interface without
any endpoint descriptors. fcp_find_fc_interface() currently selects the
first vendor-specific interface and reads endpoint 0 from it, without
checking whether the interface actually has any endpoints.

When bNumEndpoints is zero, no endpoint array is allocated for the parsed
alternate setting, so get_endpoint(..., 0) yields an invalid endpoint
descriptor pointer. Dereferencing it through usb_endpoint_num() then
triggers a NULL pointer dereference.

Skip vendor-specific interfaces that do not have any endpoints.

## Which versions are affected by CVE-2026-72403?


## How do I fix CVE-2026-72403?

Apply the vendor's patch.

## Is CVE-2026-72403 being exploited?

There is no known exploitation of CVE-2026-72403 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-72403 and fix it if it is affected.

What it is: CVE-2026-72403 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-72403 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-2026-72403/ (Markdown: https://insights.sbomify.com/CVE-2026-72403/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-72403
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72403
- OSV: https://osv.dev/vulnerability/CVE-2026-72403

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-72403/
Summaries are generated and may contain mistakes; the official description above is the record.