🟡 Medium | Source: GCP Compute Engine Security Bulletins
A hardware flaw in AMD Zen 5 (Turin) processors causes the 16-bit and 32-bit variants of the RDSEED instruction — used to generate cryptographic random numbers — to silently fail under certain load conditions. Applications that directly use these instruction widths may produce weak or predictable random numbers, undermining cryptographic security. The 64-bit variant is unaffected, meaning standard Linux kernel random number generation via /dev/[u]random is safe.
Security Architect’s Take: Audit any workloads running on AMD Zen 5 (Turin) GCP instances that directly invoke RDSEED at the application or library level — particularly custom cryptographic code or language runtimes that bypass the OS entropy pool. Ensure all such code uses the 64-bit RDSEED variant or delegates to /dev/urandom; no kernel-level patching is required at this time, but monitor AMD’s investigation for further guidance.
Original advisory: GCP-2025-058