A newly disclosed vulnerability in AMD’s latest Zen 5 architecture has raised serious concerns about the reliability of hardware-based random number generation – a cornerstone of modern cryptography and secure computing.
The Vulnerability: CVE-2025-62626 (AMD-SB-7055)
Researchers have identified a flaw in the RDSEED instruction, a critical component responsible for generating cryptographically secure random numbers in AMD Zen 5 processors. The vulnerability, tracked as CVE-2025-62626, reveals that under certain conditions, RDSEED may return zero values while incorrectly indicating success.
This seemingly minor deviation can have severe implications – as random number generation is fundamental to: – Cryptographic key creation – Session token generation – Authentication and encryption mechanisms
When RDSEED fails silently, applications relying on it for secure entropy may unknowingly generate predictable or weak keys, opening the door to cryptographic attacks and data exposure.
Impact and Risk
The RDSEED bug directly affects systems using Zen 5 CPUs, potentially impacting: – Servers and enterprise workloads using AMD Zen 5 architecture – Cloud providers leveraging AMD EPYC or Ryzen Zen 5 processors – Developers and organizations building secure applications reliant on hardware entropy sources
Cryptographic operations depending solely on RDSEED without additional entropy mixing are most vulnerable. Attackers could, in theory, exploit this weakness to infer private keys, compromise encrypted data, or bypass authentication layers.
AMD’s Response
AMD has acknowledged the issue and published a security bulletin (AMD-SB-7055) outlining the flaw’s technical details and mitigation roadmap. The company is preparing microcode and firmware updates to address the vulnerability and restore the integrity of the random number generation process.
In the meantime, security experts recommend: – Avoiding critical cryptographic operations on unpatched Zen 5 processors – Using software-based entropy sources (such as /dev/random, Fortuna, or RDRAND fallbacks) – Monitoring AMD’s official security advisories for patch releases
Key Takeaway
Hardware-level vulnerabilities like this remind us that even trusted cryptographic primitives can fail at the silicon level. Security teams must view hardware and firmware as part of the broader attack surface, integrating hardware assurance into risk management and compliance frameworks.
In today’s threat landscape, resilience is built not only on software security but also on hardware trust.
Conclusion
The AMD Zen 5 RDSEED vulnerability underscores the fragility of hardware-based security assumptions. As organizations increasingly rely on advanced CPUs for secure workloads, continuous validation, timely patching, and layered defenses become indispensable to maintaining cryptographic integrity.