CVE-2026-16661: Power System Integer Overflow

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-19 · updated 2026-08-25
Weakness: CWE-190

Description

IBM PowerVM Hypervisor FW1120.00, FW1110.00 through FW1110.30, FW1060.00 through FW1060.80, and FW950.00 through FW950.H2 is affected by a vulnerability in the service processor mailbox interface. An attacker with authenticated service-level access to the FSP can exploit this vulnerability, allowing arbitrary code to be executed in the host firmware runtime, giving full control over the managed system, resulting in a confidentiality, integrity, and availability impact to the managed system.

Affected products

IBM Power System E1050 (9043-Mrx) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System E1080 (9080-Hex) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System E1150 (9043-Mru) Firmware: from fw1110.00 before fw1110.31; fw1120.00 — fixed in fw1110.31
IBM Power System E1180 (9080-Heu) Firmware: from fw1110.00 before fw1110.31; fw1120.00 — fixed in fw1110.31
IBM Power System E950 (9040-Mr9) Firmware: from fw950.00 before fw950.h3 — fixed in fw950.h3
IBM Power System E980 (9080-M9S) Firmware: from fw950.00 before fw950.h3 — fixed in fw950.h3
IBM Power System H922 (9223-22S) Firmware: from fw950.00 before fw950.h3 — fixed in fw950.h3
IBM Power System H924 (9223-42S) Firmware: from fw950.00 before fw950.h3 — fixed in fw950.h3
IBM Power System L1022 (9786-22H) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System L1024 (9786-42H) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System L1122 (9856-22H) Firmware: from fw1110.00 before fw1110.31; fw1120.00 — fixed in fw1110.31
IBM Power System L1124 (9856-42H) Firmware: from fw1110.00 before fw1110.31; fw1120.00 — fixed in fw1110.31
IBM Power System S1012 (9028-21B) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System S1014 (9105-41B) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System S1022 (9105-22A) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System S1022S (9105-22B) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System S1024 (9105-42A) Firmware: from fw1060.00 before fw1060.81 — fixed in fw1060.81
IBM Power System S1112 (9242-21B) Firmware: fw1120.00
IBM Power System S1112 (9242-21T) Firmware: fw1120.00
IBM Power System S1114 (9824-41B) Firmware: from fw1110.00 before fw1110.31; fw1120.00 — fixed in fw1110.31
IBM Power System S1122 (9824-22A) Firmware: from fw1110.00 before fw1110.31; fw1120.00 — fixed in fw1110.31
IBM Power System S1122S (9824-22B) Firmware: from fw1110.00 before fw1110.31; fw1120.00 — fixed in fw1110.31
IBM Power System S1124 (9824-42A) Firmware: from fw1110.00 before fw1110.31; fw1120.00 — fixed in fw1110.31
IBM Power System S914 (9009-41G) Firmware: from fw950.00 before fw950.h3 — fixed in fw950.h3
IBM Power System S922 (9009-22G) Firmware: from fw950.00 before fw950.h3 — fixed in fw950.h3
IBM Power System S924 (9009-42G) Firmware: from fw950.00 before fw950.h3 — fixed in fw950.h3

How to fix

Upgrade to a fixed version: IBM Power System E1050 (9043-Mrx) Firmware fw1060.81; IBM Power System E1080 (9080-Hex) Firmware fw1060.81; IBM Power System E1150 (9043-Mru) Firmware fw1110.31; IBM Power System E1180 (9080-Heu) Firmware fw1110.31; IBM Power System E950 (9040-Mr9) Firmware fw950.h3; IBM Power System E980 (9080-M9S) Firmware fw950.h3; IBM Power System H922 (9223-22S) Firmware fw950.h3; IBM Power System H924 (9223-42S) Firmware fw950.h3; IBM Power System L1022 (9786-22H) Firmware fw1060.81; IBM Power System L1024 (9786-42H) Firmware fw1060.81; IBM Power System L1122 (9856-22H) Firmware fw1110.31; IBM Power System L1124 (9856-42H) Firmware fw1110.31. Check the vendor advisory for mitigations.

References

https://www.ibm.com/support/pages/node/7283237

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