CVE-2021-20505

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

Published: 2021-07-29 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-20505 is rated Low Risk (26.2/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.10%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-20505

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-03-30 0.25% 0.10% -0.15%
2 2025-03-29 0.10% 0.25% +0.15%
3 2025-03-17 — 0.10% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-20505

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.4 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 0.7 3.6 [email protected]
4.4 3.0 MEDIUM
CVSS:3.0/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 0.7 3.6 [email protected]
3.5 2.0 LOW
AV:N/AC:M/Au:S/C:P/I:N/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 6.8 2.9 [email protected]

Weakness enumeration for CVE-2021-20505

Affected software / configurations for CVE-2021-20505

Vendor Product Version Raw CPE
ibm powervm_hypervisor fw920 cpe:2.3:o:ibm:powervm_hypervisor:fw920:*:*:*:*:*:*:*
ibm powervm_hypervisor fw930 cpe:2.3:o:ibm:powervm_hypervisor:fw930:*:*:*:*:*:*:*
ibm powervm_hypervisor fw940 cpe:2.3:o:ibm:powervm_hypervisor:fw940:*:*:*:*:*:*:*
ibm powervm_hypervisor fw950 cpe:2.3:o:ibm:powervm_hypervisor:fw950:*:*:*:*:*:*:*

References for CVE-2021-20505

cvelogic Threat Intelligence