CVE-2021-20487

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-05-26 · updated 2026-06-17
Weakness: CWE-347

Description

IBM Power9 Self Boot Engine(SBE) could allow a privileged user to inject malicious code and compromise the integrity of the host firmware bypassing the host firmware signature verification process.

Affected products

IBM Power9 System Firmware: from fw930.00 before fw930.30; from fw940.00 before fw940.20; before fw950.00 — fixed in fw930.30, fw940.20, fw950.00
IBM Scale-Out Lc System Firmware: before op940.20 — fixed in op940.20

How to fix

Upgrade to a fixed version: IBM Power9 System Firmware fw930.30, fw940.20, fw950.00; IBM Scale-Out Lc System Firmware op940.20. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2021-20487 or the next vulnerability affects your stack