Researchers discovered a critical vulnerability in AMD's Zen CPUs, termed 'EntrySign,' which allows attackers with high privileges to install malicious microcode by exploiting the AES-CMAC algorithm's flaw used in validation processes. This vulnerability affects AMD Zen architecture CPUs from versions 1 to 4, enabling attackers to bypass cryptographic checks and potentially gain persistent access to manipulate the processors' instruction set. The impact of such an attack could be especially severe if the compromised CPUs are used in cloud services and AI infrastructures, posing risks to data integrity, system reliability, and the security posture of affected entities.
Source: https://cybersecuritynews.com/amd-microcode-signature-verification-vulnerability/
"id": "AMD658030725",
"linkid": "AMD",
"type": "Vulnerability",
"date": "3/2025",
"severity": "100",
"impact": "5",
"explanation": "Attack threatening the organization’s existence"