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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Not stated
- Victim action needed
- Not needed
- Fix
- Available
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.
Sources
Also known as DEBIAN-CVE-2022-50731, GHSA-26jg-99jv-7wgw, UBUNTU-CVE-2022-50731.