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Vulnerability record · CVE-2026-18821 · published 19 August 2026

CVE-2026-18821: Ibm power system s1122 \(9824-22a\) firmware out-of-bounds write vulnerability

Ibm · Power System S1122 \(9824 22a\) Firmware

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.

8.8 CVSS 3.1 High EPSS 0.20% · top 91.7% CWE-787 · Out-of-bounds write
8.8CVSS 3.1 base score
0.20%EPSS exploitation probability, 30 days
NoNot in CISA KEV
26Affected product versions listed by NVD
1References
25 Aug 2026Last modified by NVD

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.

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

26 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://www.ibm.com/support/pages/node/7283232 Vendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-18821), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.