CVE-2021-20487Network attack vector

Firmware compromise via Self Boot Engine code injection

Published May 26, 2021 · Updated Sep 16, 2024

Code injection in IBM Power Systems Power9 Self Boot Engine allows remote authenticated users to compromise host firmware integrity. The Self Boot Engine accepts malicious code from a compromised service processor without enforcing the host firmware signature verification boundary. Root access to the service processor is required, and the resulting firmware compromise is not detectable through TPM attestation.

CVSS severity8.0
High
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code injection in IBM Power Systems Power9 Self Boot Engine allows remote authenticated users to compromise host firmware integrity. The Self Boot Engine accepts malicious code from a compromised service processor without enforcing the host firmware signature verification boundary. Root access to the service processor is required, and the resulting firmware compromise is not detectable through TPM attestation.

The record

CVE
CVE-2021-20487
Published
May 26, 2021
Updated
Sep 16, 2024
Vendor
IBM
Product
IBM Power Systems
Classifications
CWE-347, T1542.001
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. May 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=FW930
  2. Affected versionversion=FW940
  3. Affected versionversion=FW941
  4. Affected versionversion=OP940

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

IBM · IBM Power Systemsversion=FW930; version=FW940; version=FW941; version=OP940

Published CVSS scores

8.0IBM CorporationCVSS:3.0/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1542.001Pre-OS Boot: System Firmware

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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