Timing Side-Channel in AMD ASP HMAC Enables Brute-Force for Integrity Breach
CVE-2023-20540 Published on June 26, 2026
An observable timing discrepancy in the ASP could allow a privileged attacker to perform a brute-force attack against the hash message authentication code, allowing arbitrary message input, potentially leading to a loss of data integrity.
Weakness Type
Observable Timing Discrepancy
Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not. In security-relevant contexts, even small variations in timing can be exploited by attackers to indirectly infer certain details about the product's internal operations. For example, in some cryptographic algorithms, attackers can use timing differences to infer certain properties about a private key, making the key easier to guess. Timing discrepancies effectively form a timing side channel.
Affected Versions
AMD Ryzen™ 3000 Series Desktop Processors:- Version ComboAM4 1.0.0.E is unaffected.
- Version ComboAM4v2PI 1.2.0.CA is unaffected.
- Version ComboAM4v2PI 1.2.0.CA is unaffected.
- Version CastlePeakPI-SP3r3 1.0.0.C is unaffected.
- Version CastlePeakWSPI-sWRX8 1.0.0.E is unaffected.
- Version ChagallWSPI-sWRX8 1.0.0.9 is unaffected.