CVE-2026-18821
Power System Out-of-bounds Write
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.
Attack profile
How easy it is to exploit
- Attack vector
- Adjacent network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
7.5
Power System Out-of-bounds Write
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.
- Record
CVE-2026-18821- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-787
- Updated
- 2026-11-02
EUVDEUVD-2026-62876
7.5
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.
- Record
EUVD-2026-62876- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-3c3p-64wc-c8w7
7.5
IBM PowerVM Hypervisor FW1120.00, FW1110.00 through FW1110.30, FW1060.00 through FW1060.80, and...
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.
- Record
GHSA-3c3p-64wc-c8w7- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-787
- Updated
- 2026-11-02
NVD
7.5
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.
- Record
CVE-2026-18821- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 3.1
- 8.8 High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-787
- Updated
- 2026-11-02
Affected products
- ibm powervm hypervisor
- ibm power system e1050 \(9043-mrx\) firmware
- ibm power system e1080 \(9080-hex\) firmware
- ibm power system e1150 \(9043-mru\) firmware
- ibm power system e1180 \(9080-heu\) firmware
- ibm power system e950 \(9040-mr9\) firmware
- ibm power system e980 \(9080-m9s\) firmware
- ibm power system h922 \(9223-22s\) firmware
- ibm power system h924 \(9223-42s\) firmware
- ibm power system l1022 \(9786-22h\) firmware
- ibm power system l1024 \(9786-42h\) firmware
- ibm power system l1122 \(9856-22h\) firmware
Show 15 moreShow less
- ibm power system l1124 \(9856-42h\) firmware
- ibm power system s1012 \(9028-21b\) firmware
- ibm power system s1014 \(9105-41b\) firmware
- ibm power system s1022 \(9105-22a\) firmware
- ibm power system s1022s \(9105-22b\) firmware
- ibm power system s1024 \(9105-42a\) firmware
- ibm power system s1112 \(9242-21b\) firmware
- ibm power system s1112 \(9242-21t\) firmware
- ibm power system s1114 \(9824-41b\) firmware
- ibm power system s1122 \(9824-22a\) firmware
- ibm power system s1122s \(9824-22b\) firmware
- ibm power system s1124 \(9824-42a\) firmware
- ibm power system s914 \(9009-41g\) firmware
- ibm power system s922 \(9009-22g\) firmware
- ibm power system s924 \(9009-42g\) firmware
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-18821 is a high vulnerability (CVSS 7.5) in Ibm Powervm Hypervisor, published August 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.29%, the 21st percentile. No source names a fixed version.