# CVE-2026-74500: ALSA: usb-audio: fix stack info leak in RME Digiface status

> A local attacker can read uninitialized kernel stack memory via USB audio status controls, potentially exposing sensitive data.

- **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:** 15 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** BELL-CVE-2026-74500, DEBIAN-CVE-2026-74500, GHSA-fgmp-3fcj-wj99, UBUNTU-CVE-2026-74500

## What is CVE-2026-74500?

CVE-2026-74500 is a 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:

ALSA: usb-audio: fix stack info leak in RME Digiface status

snd_rme_digiface_read_status() reads a four-word status block from the
device into an uninitialised on-stack __le32 buf[4] and, whenever the
vendor control-IN transfer does not return a negative error, copies all
four words into the caller's status[].

snd_usb_ctl_msg() copies the full requested size back into the caller's
buffer regardless of how many bytes the data stage actually delivered:

	buf = kmemdup(data, size, GFP_KERNEL);
	err = usb_control_msg(dev, pipe, request, requesttype,
			      value, index, buf, size, timeout);
	memcpy(data, buf, size);

usb_control_msg() returns the transferred length on a short control-IN,
which is a non-negative value, and writes only that many bytes.  The
remainder of the copy back is the kmemdup()ed image of the caller's
buffer, so a device answering with a short data stage leaves the
trailing words of buf[] holding leftover kernel stack.  The only guard
in the caller is err < 0, so those words are stored into status[].

They then reach user space: snd_rme_digiface_get_status_val() selects a
16-bit halfword of status[] per the control's reg/mask, and the eight
Digiface status controls together expose the whole 16-byte frame to an
unprivileged reader of /dev/snd/controlC*.

Zero-initialise the buffer so a short read yields zeros instead of stack
residue.  This mirrors snd_rme_get_status1(), which already clears its
output word before the same kind of vendor read.

Discovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>

## Which versions are affected by CVE-2026-74500?


## How do I fix CVE-2026-74500?

Apply the vendor's patch.

## Is CVE-2026-74500 being exploited?

There is no known exploitation of CVE-2026-74500 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-74500 and fix it if it is affected.

What it is: CVE-2026-74500 is a 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-2026-74500 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-2026-74500/ (Markdown: https://insights.sbomify.com/CVE-2026-74500/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-74500
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-74500
- OSV: https://osv.dev/vulnerability/CVE-2026-74500

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-74500/
Summaries are generated and may contain mistakes; the official description above is the record.