The Linux kernel contained a vulnerability in the AMD Zen5 CPU RDSEED instruction implementation. Specifically, the 16-bit and 32-bit register output variants of RDSEED could return a random value of zero more frequently than expected, violating randomness assumptions, and incorrectly indicate success via the carry flag (CF=1). This undermines the reliability of the random number generation, potentially affecting cryptographic operations relying on RDSEED. The issue is tracked as CVE-2025-68313. The fix involves adding microcode revision checks to ensure proper behavior.

The vulnerability compromises the confidentiality and integrity of random values generated by the RDSEED instruction on affected AMD Zen5 CPUs. This can lead to predictable or weak random numbers being used in security-sensitive operations, potentially undermining cryptographic processes that depend on high-quality randomness. The CVSS vector indicates local attack complexity and privileges required, with no user interaction needed, and a high impact on confidentiality and integrity but no impact on availability.

A fix has been implemented in the Linux kernel that adds microcode revision checks to address the RDSEED issue on AMD Zen5 CPUs. Users should apply the official Linux kernel updates that include this fix. Since this is a kernel-level vulnerability, updating to the patched kernel version is the recommended remediation. Patch status is not explicitly confirmed in the provided data; users should consult the Linux kernel vendor advisory or distribution security notices for the exact patched versions and update instructions.