Security readout for executives and security teams
Plain-English summary
This flaw affects IBM Power9 firmware. A highly privileged user could inject malicious code and bypass host firmware signature checks, potentially undermining trust in the server platform itself.
Executive priority
Treat as high priority for IBM Power9 estates because firmware compromise can undermine platform trust and recovery confidence, even though exploitation requires privileged access.
Technical view
IBM Power9 Self Boot Engine could allow malicious code injection and compromise host firmware integrity by bypassing firmware signature verification. The CVSS 3.0 score is 8.0, with high privilege and high complexity required.
Likely exposure
Exposure is likely limited to organizations operating IBM Power 9 Systems on firmware lines FW930, FW940, FW941, or OP940.
Exploitation context
The provided sources do not show known active exploitation. The CVSS vector indicates network reachability, no user interaction, high privileges, high complexity, and high impact.
Researcher notes
The bundle names affected firmware families but does not include CWE, exploit details, or exact fixed levels. Use IBM guidance as the authoritative source for remediation specifics.
Mitigation direction
- Inventory IBM Power 9 Systems and record installed firmware levels.
- Review IBM advisory 6455911 for the vendor-approved remediation path.
- Update affected firmware using IBM-supported maintenance procedures.
- Restrict privileged firmware administration access until remediation is complete.
- Monitor firmware change records for unauthorized or unexplained activity.
Validation and detection
- Confirm whether systems run FW930, FW940, FW941, or OP940.
- Compare installed firmware with IBM advisory guidance.
- Verify remediation through firmware version evidence after maintenance.
- Review privileged access paths to firmware management interfaces.
- Check change logs for unexpected firmware or boot-chain modifications.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-20487 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/UI:N/I:H/AC:H/PR:H/S:C/A:H/C:H/E:U/RL:O/RC:C
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/UI:N/I:H/AC:H/PR:H/S:C/A:H/C:H/E:U/RL:O/RC:C1.36Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8HighVector: CVSS:3.0/AV:N/UI:N/I:H/AC:H/PR:H/S:C/A:H/C:H/E:U/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://www.ibm.com/support/pages/node/6455911CVE reference · x_refsource_CONFIRM
- ibm-power9-cve202120487-priv-escalation (197730)CVE reference · vdb-entry, x_refsource_XF
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.