AMD Zen 5 Processors RDSEED Vulnerability Breaks Integrity With Randomness
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AMD has disclosed a critical vulnerability affecting its Zen 5 processor lineup that compromises the reliability of random number generation, a fundamental security feature in modern computing.<\/p>\n
The flaw, tracked as CVE-2025-62626, impacts the RDSEED instruction used by systems to generate cryptographically secure random numbers essential for encryption<\/a>, authentication, and other security operations.<\/p>\n The vulnerability stems from a defect in the RDSEED instruction implementation on Zen 5 processors. Under certain conditions, the instruction returns a value of zero while incorrectly signaling success through the carry flag (CF=1).<\/p>\n This behavior creates a dangerous scenario where software believes it has received a valid random number when it has actually obtained a predictable zero value. The issue affects both 16-bit and 32-bit forms of the RDSEED instruction, though the 64-bit version remains unaffected.<\/p>\n AMD learned about this bug through an unconventional channel. The issue was first reported publicly on the Linux kernel<\/a> mailing list rather than through AMD\u2019s standard Coordinated Vulnerability Disclosure process.<\/p>\n This public disclosure path highlights the collaborative nature of open-source security research but also underscores the challenge of managing security information across diverse reporting channels.<\/p>\n The severity of this vulnerability cannot be understated. Random number generation forms the backbone of cryptographic security in modern systems.<\/p>\n When RDSEED fails silently by returning zeros while indicating success, applications may generate weak encryption keys, predictable authentication tokens, or compromised security protocols<\/a>.<\/p>\nUnderstanding the RDSEED Flaw<\/strong><\/h2>\n