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CVE Record

CVE-2021-20505: The PowerVM Logical Partition Mobility(LPM) (PowerVM Hypervisor FW920, FW930, FW940, and FW950) encryption...

The PowerVM Logical Partition Mobility(LPM) (PowerVM Hypervisor FW920, FW930, FW940, and FW950) encryption key exchange protocol can be compromised. If an attacker has the ability to capture encrypted LPM network traffic and is able to gain service access to the FSP they can use this information to perform a series of PowerVM service procedures to decrypt the captured migration traffic IBM X-Force ID: 198232

MediumCVSS 4.4Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This flaw affects IBM PowerVM Logical Partition Mobility encryption during virtual machine migration. An attacker would need both captured encrypted migration traffic and privileged service access to the Flexible Service Processor. If those conditions are met, confidential migration data could be decrypted.

Executive priority

Treat this as a targeted confidentiality risk for IBM Power virtualization environments, not a broad internet emergency. Prioritize if regulated workloads move through LPM or if FSP administration is shared, remote, or weakly monitored.

Technical view

CVE-2021-20505 is a compromise of the PowerVM LPM encryption key exchange protocol in PowerVM Hypervisor FW920, FW930, FW940, and FW950. The disclosed impact is confidentiality loss only, with high privileges and high attack complexity required.

Likely exposure

Exposure is most likely in IBM Power systems using affected PowerVM Hypervisor firmware and Logical Partition Mobility. Risk concentrates around environments where migration networks can be observed and FSP service access is broadly available or poorly controlled.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation. Exploitation requires capturing encrypted LPM network traffic and obtaining FSP service access, making opportunistic internet exploitation unlikely from the provided evidence.

Researcher notes

The bundle provides affected firmware families, CVSS 4.4, and prerequisites, but not detailed fixed versions. Avoid inferring exploit availability or patches beyond IBM advisory guidance. Key validation areas are LPM usage, migration traffic exposure, and FSP service-access control.

Mitigation direction

  • Review IBM support advisory for official remediation guidance.
  • Update affected PowerVM firmware according to IBM guidance.
  • Restrict FSP service access to authorized administrators only.
  • Isolate LPM migration traffic on trusted management networks.
  • Monitor FSP access and LPM activity for unusual behavior.

Validation and detection

  • Inventory PowerVM Hypervisor firmware versions FW920, FW930, FW940, and FW950.
  • Confirm whether Logical Partition Mobility is enabled.
  • Verify LPM networks are not reachable from untrusted segments.
  • Review FSP account access, roles, and recent service activity.
  • Check IBM guidance for current fixed firmware or required procedures.
Prepared
Confidence
high
Sources
4

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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

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CVE-2021-20505 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.4 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/UI:N/S:U/I:N/C:H/AC:H/PR:H/AV:N/A:N/RC:C/RL:O/E:U

Official CVE source material

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.

1CVSS vectors
0Timeline events
0ADP providers
3Source links

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
4.4CVSS 3.0MediumCVSS:3.0/UI:N/S:U/I:N/C:H/AC:H/PR:H/AV:N/A:N/RC:C/RL:O/E:U0.73.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

4.4Medium
CVSS 3.0 vector shape for CVE-2021-20505Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/UI:N/S:U/I:N/C:H/AC:H/PR:H/AV:N/A:N/RC:C/RL:O/E:U

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
IBMPowerVM HypervisorFW920, FW930, FW940, FW950Listed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.