CVE-2021-26328 Security feature bypass in 3rd Gen EPYC

Medium 4.4 Published 10 Jan 2023 Updated 9 Apr 2025

Attackers can compromise memory integrity for Secure Nested Paging guests by exploiting a missing CPU execution mode check during initialization.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2021-26328?

CVE-2021-26328 is a medium-severity vulnerability in Amd Epyc 72f3 Firmware, published on 10 Jan 2023. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

Failure to verify the mode of CPU execution at the time of SNP_INIT may lead to a potential loss of memory integrity for SNP guests.

Weakness: CWE-358

Which versions are affected by CVE-2021-26328?

It affects 24 products.

Products include Amd Epyc 7003 Firmware, Amd Epyc 72f3 Firmware, Amd Epyc 7313 Firmware, Amd Epyc 7313p Firmware, Amd Epyc 7343 Firmware, Amd Epyc 7373x Firmware and 18 more.

How do I fix CVE-2021-26328?

No fix has been published for CVE-2021-26328 yet. Limit exposure of the affected software until one is available.

Is CVE-2021-26328 being exploited?

There is no known exploitation of CVE-2021-26328 in the wild and no public exploit code.

All Amd Epyc 72f3 Firmware vulnerabilities

Sources

Also known as GHSA-fg37-647w-pgrp.