CVE-2026-18821
Received Received - Intake

IBM PowerVM Hypervisor Firmware Network Boot Code Execution

Publication date: 2026-08-19

Last updated on: 2026-08-19

Assigner: IBM Corporation

Description
IBM PowerVM Hypervisor FW1120.00, FW1110.00 through FW1110.30, FW1060.00 through FW1060.80, and FW950.00 through FW950.H2 Power Systems Firmware is affected by a vulnerability in partition firmware during network boot. An unauthenticated attacker on the same network as a partition undergoing network boot can send a malformed packet, allowing arbitrary code to be executed in the partition firmware and compromising everything subsequently loaded by that partition. Other partitions and the managed system are not affected. Only partitions actively performing a network boot are affected, resulting in a confidentiality, integrity, and availability impact.

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Meta Information

Published
2026-08-19
Last Modified
2026-08-19
Generated
2026-08-20
AI Q&A
2026-08-19
EPSS Evaluated
N/A
NVD
CVE-2026-18821
EUVD
EUVD-2026-62876

Affected Vendors & Products

Showing 7 associated CPEs
Vendor Product Version / Range
ibm powervm_hypervisor From FW1110.00 (inc) to FW1110.30 (inc)
ibm powervm_hypervisor From FW1060.00 (inc) to FW1060.80 (inc)
ibm powervm_hypervisor From FW950.00 (inc) to FW950.H2 (inc)
ibm powervm_hypervisor fw1120.00
ibm powervm_hypervisor From fw1110.00 (inc) to fw1110.30 (inc)
ibm powervm_hypervisor From fw1060.00 (inc) to fw1060.80 (inc)
ibm powervm_hypervisor From fw950.00 (inc) to fw950.h2 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-787 The product writes data past the end, or before the beginning, of the intended buffer.

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Executive Summary

CVE-2026-18821 is a vulnerability in IBM PowerVM Hypervisor firmware affecting partition firmware during network boot. An unauthenticated attacker on the same network as a partition performing a network boot can send a malformed packet to execute arbitrary code in the partition firmware. This compromises everything loaded by that partition, impacting confidentiality, integrity, and availability.

Detection Guidance

Detecting this vulnerability requires monitoring network traffic during partition network boot operations. Check for malformed packets sent to the booting partition's IP address. Use network sniffing tools like tcpdump or Wireshark to capture boot-related traffic and look for anomalies in DHCP, TFTP, or PXE protocols during boot sequences.

Impact Analysis

If you are using affected IBM Power Systems firmware versions, an attacker on the same network could exploit this during a network boot to execute arbitrary code in the partition firmware. This could lead to unauthorized access, data breaches, system crashes, or further compromise of the partition's operating system and applications.

Compliance Impact

This vulnerability could lead to unauthorized access and data breaches, which may violate GDPR's data protection requirements or HIPAA's security and privacy rules. Organizations using affected systems may face compliance violations, legal penalties, and reputational damage if exploited.

Mitigation Strategies

Immediately update the firmware of affected Power Systems to the latest versions provided by IBM for Power 9, Power 10, and Power 11 systems. Isolate network segments where partitions perform network boot to limit exposure. Disable network boot for non-essential partitions until patches are applied.

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