CVE-2026-4936: CWE-331 Insufficient Entropy in IBM PowerVM Hypervisor
Description
CVE-2026-4936 is a vulnerability in IBM PowerVM Hypervisor's Platform KeyStore (PKS) and virtual TPM firmware versions FW1110.00 through FW1110.20, FW1060.00 through FW1060.71, and FW950.00 through FW950.H2. The issue involves the use of persistent storage key seeds that produce an AES key with reduced cryptographic strength due to insufficient entropy. An attacker with high-level access to the service processor or Hardware Management Console (HMC) could potentially derive the encryption key and gain unauthorized access to protected data.
CVSS v3.1
Score 5.1medium
Affected software
IBM
PowerVM Hypervisor
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
IBM PowerVM Hypervisor Platform KeyStore (PKS) and virtual TPM firmware versions FW1110.00-FW1110.20, FW1060.00-FW1060.71, and FW950.00-FW950.H2 use persistent storage key seeds that result in AES keys with reduced strength due to insufficient entropy (CWE-331). This cryptographic weakness could allow an attacker with access to the service processor or HMC to derive the encryption key and access sensitive data. The CVSS 3.1 score is 5.1 (medium severity), reflecting the attack vector as adjacent network with high complexity and high privileges required, and user interaction needed. Confidentiality impact is high, while integrity and availability impacts are none.
Potential Impact
The vulnerability allows an attacker with high privileges and access to the service processor or HMC to derive encryption keys protecting data, potentially leading to unauthorized disclosure of sensitive information. There is no impact on data integrity or availability. The medium CVSS score reflects the difficulty of exploitation due to required privileges and user interaction.
Mitigation Recommendations
No patch or official fix information is provided in the available data. Patch status is not yet confirmed — check the IBM vendor advisory for current remediation guidance. Until a fix is available, restrict access to the service processor and HMC to trusted personnel only to reduce risk.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- ibm
- Date Reserved
- 2026-03-26T20:32:20.576Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a86e0f3acd9273b49838512
Added to database: 08/20/2026, 11:11:47 UTC
Last enriched: 09/11/2026, 05:18:07 UTC
Last updated: 10/04/2026, 18:53:16 UTC
Views: 84
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