# CVE-2021-47650: ASoC: soc-compress: prevent the potentially use of null pointer

> A null pointer dereference in the Linux kernel's ASoC compress driver can cause a system crash when registering a sound card with zero codecs.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Feb 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-47650, GHSA-ff4j-xjhx-jpxp, UBUNTU-CVE-2021-47650

## What is CVE-2021-47650?

CVE-2021-47650 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 2025. 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:

ASoC: soc-compress: prevent the potentially use of null pointer

There is one call trace that snd_soc_register_card()
->snd_soc_bind_card()->soc_init_pcm_runtime()
->snd_soc_dai_compress_new()->snd_soc_new_compress().
In the trace the 'codec_dai' transfers from card->dai_link,
and we can see from the snd_soc_add_pcm_runtime() in
snd_soc_bind_card() that, if value of card->dai_link->num_codecs
is 0, then 'codec_dai' could be null pointer caused
by index out of bound in 'asoc_rtd_to_codec(rtd, 0)'.
And snd_soc_register_card() is called by various platforms.
Therefore, it is better to add the check in the case of misusing.
And because 'cpu_dai' has already checked in soc_init_pcm_runtime(),
there is no need to check again.
Adding the check as follow, then if 'codec_dai' is null,
snd_soc_new_compress() will not pass through the check
'if (playback + capture != 1)', avoiding the leftover use of
'codec_dai'.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-47650?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47650?

Apply the vendor's patch.

## Is CVE-2021-47650 being exploited?

There is no known exploitation of CVE-2021-47650 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-47650 and fix it if it is affected.

What it is: CVE-2021-47650 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 2025. 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-2021-47650 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2021-47650/ (Markdown: https://insights.sbomify.com/CVE-2021-47650/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47650
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47650
- OSV: https://osv.dev/vulnerability/CVE-2021-47650

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47650/
Summaries are generated and may contain mistakes; the official description above is the record.