CVE-2021-20487
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIBM 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.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIBM Power9 Self Boot Engine (SBE) contains a vulnerability allowing a privileged attacker to bypass host firmware signature verification, enabling injection of malicious code into the host firmware. The SBE is responsible for initial boot processes on Power9 processors, and this flaw compromises the chain of trust at the most fundamental level.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= fw930.00, < fw930.30>= fw940.00, < fw940.20< fw950.00< op940.20CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Power9 System Firmware versionUse the IBM service processor or BMC interface (e.g., via IPMI, Redfish, or ASMI) to retrieve the current system firmware level. On AIX systems, run 'lsattr -El sys0' or use 'lsmcode -A'. On Linux, check /proc/device-tree or use ipmi commands.Affected if The firmware version matches >= fw930.00 and < fw930.30, OR >= fw940.00 and < fw940.20, OR is < fw950.00
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Identify IBM Scale Out Logic (LC) System Firmware versionFor Scale Out Logic systems, retrieve the OP940 firmware version through the BMC web interface, IPMI command 'ipmi sel list', or the IBM Flexible Service Processor (FSP).Affected if The OP940 firmware version is < op940.20
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Verify SBE firmware versionAccess the Self Boot Engine firmware level through the IBM service processor or by running 'lsvpd' command on AIX/Linux to extract Vital Product Data (VPD) which includes SBE level information.Affected if The SBE firmware version corresponds to an affected fw930, fw940, or pre-op940.20 release
The system is affected if the Power9 System Firmware version is fw930.00 through fw930.29, fw940.00 through fw940.19, or any version below fw950.00, or if the Scale Out Logic OP940 firmware is below op940.20.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply IBM-provided firmware updates for the Power9 SBE. Organizations should prioritize updating affected systems given the critical severity and the ability for privileged users to bypass signature verification.
- Consultation8.0 h
- Implementation16.0 h
- Testing12.0 h
- Review / QA8.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $12,352.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20487 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-20487 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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