Bug 2422831 (CVE-2025-68313)

Summary: CVE-2025-68313 kernel: Linux kernel: Denial of Service due to inconsistent random number generation on AMD Zen5 processors
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel. A local user could exploit a vulnerability in the RDSEED (Random Seed) instruction on AMD Zen5 processors. This issue causes the RDSEED instruction to return a random value of zero, which is inconsistent with expected randomness and incorrectly signals success. This can lead to a denial of service (DoS) by compromising operations that rely on high-quality random number generation.
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Description OSIDB Bzimport 2025-12-16 16:04:53 UTC 
In the Linux kernel, the following vulnerability has been resolved:

x86/CPU/AMD: Add RDSEED fix for Zen5

There's an issue with RDSEED's 16-bit and 32-bit register output
variants on Zen5 which return a random value of 0 "at a rate inconsistent
with randomness while incorrectly signaling success (CF=1)". Search the
web for AMD-SB-7055 for more detail.

Add a fix glue which checks microcode revisions.

  [ bp: Add microcode revisions checking, rewrite. ]
Comment 1 Alexander B 2025-12-16 17:49:47 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025121654-CVE-2025-68313-c65d@gregkh/T