Linux Kernel Vulnerability in s390/pkey Implementation

CVE-2026-64558

What is CVE-2026-64558?

A vulnerability has been identified in the Linux kernel's s390/pkey implementation. Specifically, the issue arises in the key_to_protkey() handler function, where there was a lack of validation regarding the length of the target buffer. If an output exceeds the maximum buffer length, it can lead to unpredictable behavior or system instability. The vulnerability has been addressed by implementing an explicit length check in the pkey_pckmo handler, ensuring that any output generated is appropriately constrained to fit within the provided target buffer size. Users are encouraged to update their kernel versions to mitigate potential risks associated with this vulnerability.

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