# CVE-2022-50731: CVE-2022-50731

Status: published. Published: 2025-12-24. Updated: 2026-11-10.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

Not reported in collected sources.

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/779a9930f3e152c82699feb389a0e6d6644e747e (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/85bc736a18b872f54912e8bb70682d11770aece0 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/95c4e20adc3ea00d1594a2a05d9b187ed12ffa8e (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/a1354bdd191d533211b7cb723aa76a66f516f197 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/bc155c6c188c2f0c5749993b1405673d25a80389 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/f9058178597059d6307efe96a7916600f8ede08c (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50731; retrieved 2026-11-10; source updated 2026-11-10

Revision: 77be0560a0dbdba451b7faedf160a2e259bfdc35f03bdfde30d556a445bb4837

Canonical: https://y2.dev/cve/CVE-2022-50731

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