CVE-2021-26355 Denial of service in 3rd Gen EPYC

Medium 5.5 Published 10 Jan 2023 Updated 9 Apr 2025

Insufficient checks in AMD EPYC SMU allow access to invalid registers, potentially causing a denial of service.

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-2021-26355?

CVE-2021-26355 is a medium-severity denial of service 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

Insufficient fencing and checks in System Management Unit (SMU) may result in access to invalid message port registers that could result in a potential denial-of-service.

Weakness: CWE-693

Which versions are affected by CVE-2021-26355?

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-2021-26355?

No fix has been published for CVE-2021-26355 yet. Limit exposure of the affected software until one is available.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2021-26355 being exploited?

There is no known exploitation of CVE-2021-26355 in the wild and no public exploit code.

All Amd Epyc 72f3 Firmware vulnerabilities

Sources

Also known as GHSA-p4w7-qphw-gm3c.