- AMD Zen 5 chips have RDSEED flaw that puts cryptographic key integrity at risk
- A faulty RDSEED can return zeros, allowing attackers to reconstruct private keys and break encryption
- AMD recommends turning to 64-bit RDSEED or software alternatives
Some AMD processors, including those built with the latest Zen 5 architecture, have a critical vulnerability that affects cryptographic operations and therefore seriously puts the integrity of protected data at risk.
In a security bulletin, AMD detailed a flaw called “AMD-SB-7055,” describing it as a vulnerability in the RDSEED hardware-based random number generator.
On affected chips, the 16-bit and 32-bit forms of the RDSEED instruction can return “0” at a rate that is not completely random while still labeling the process as successful. In theory, if a company runs a server that generates cryptographic keys to encrypt customer data and the software running on that server uses RDSEED instructions to obtain random numbers directly from the chip, the instruction could return only zeros.
Patches and mitigations
While it’s obviously not entirely random, it would still be a sign that it was successful, without raising any red flags.
As a result, attackers who obtain one of the public keys can mathematically reconstruct or guess the private key, breaking the encryption or impersonating the company, meaning that encrypted customer records, API tokens, or even software update signatures could be forged or decrypted.
Mitigations and patches are already being worked on. By January 2026, depending on the CPU, most should have been mitigated.
Fixes for AMD’s consumer Zen 5 chips, including the Ryzen 9000, AI Max 300, Threadripper 9000, and Ryzen Z2 series, will be released on November 25.
AMD added that it should have the necessary AGESA microcode updates “soon” to rectify this issue on all Zen 5 CPUs.
If you are running chips that do not yet have a functional mitigation, AMD recommends reverting to its unaffected 64-bit RDSEED form or moving to recovery software until it is released.
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