CVE-2022-50731
Unknown Unknown - Not Provided
Null Pointer Dereference in Linux Kernel akcipher Private Key Handling

Publication date: 2025-12-24

Last updated on: 2025-12-24

Assigner: kernel.org

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.
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Meta Information
Published
2025-12-24
Last Modified
2025-12-24
Generated
2026-05-07
AI Q&A
2025-12-24
EPSS Evaluated
2026-05-05
NVD
CVE-2022-50731
EUVD
EUVD-2022-55758
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
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KEV
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CWE ID Description
CWE-UNKNOWN
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability occurs in the Linux kernel's crypto subsystem, specifically in the akcipher module's default implementation for setting a private key. Some akcipher algorithms, like ECDSA, only support signature verification and do not implement all required callbacks, including set_priv_key. When the kernel tries to set a private key on such an akcipher transform that lacks this callback, it results in a kernel crash due to a NULL pointer dereference. The patch fixes this by removing the default implementation from set_pub_key and ensuring that an error is returned instead of crashing when set_priv_key is called on unsupported algorithms.


How can this vulnerability impact me? :

This vulnerability can cause the Linux kernel to crash when attempting to set a private key on certain akcipher algorithms that do not support signature generation. This can lead to system instability or denial of service, as the kernel encounters a NULL pointer dereference and crashes instead of handling the error gracefully.


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