# CVE-2022-50731: crypto: akcipher - default implementation for setting a private key

> A null pointer dereference in the Linux kernel crypto subsystem allows local attackers to cause a denial of service by triggering a crash.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-50731, GHSA-26jg-99jv-7wgw, UBUNTU-CVE-2022-50731

## What is CVE-2022-50731?

CVE-2022-50731 is a vulnerability in Linux, published on 24 Dec 2025. 

### Official description

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

crypto: akcipher - default implementation for setting a private key

Changes from v1:
  * removed the default implementation from set_pub_key: it is assumed that
    an implementation must always have this callback defined as there are
    no use case for an algorithm, which doesn't need a public key

Many akcipher implementations (like ECDSA) support only signature
verifications, so they don't have all callbacks defined.

Commit 78a0324f4a53 ("crypto: akcipher - default implementations for
request callbacks") introduced default callbacks for sign/verify
operations, which just return an error code.

However, these are not enough, because before calling sign the caller would
likely call set_priv_key first on the instantiated transform (as the
in-kernel testmgr does). This function does not have a default stub, so the
kernel crashes, when trying to set a private key on an akcipher, which
doesn't support signature generation.

I've noticed this, when trying to add a KAT vector for ECDSA signature to
the testmgr.

With this patch the testmgr returns an error in dmesg (as it should)
instead of crashing the kernel NULL ptr dereference.

## Which versions are affected by CVE-2022-50731?


## How do I fix CVE-2022-50731?

Apply the vendor's patch.

## Is CVE-2022-50731 being exploited?

There is no known exploitation of CVE-2022-50731 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-50731 and fix it if it is affected.

What it is: CVE-2022-50731 is a vulnerability in Linux, published on 24 Dec 2025. 
Exploitation: There is no known exploitation of CVE-2022-50731 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-2022-50731/ (Markdown: https://insights.sbomify.com/CVE-2022-50731/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-50731
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50731
- OSV: https://osv.dev/vulnerability/CVE-2022-50731

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-50731/
Summaries are generated and may contain mistakes; the official description above is the record.