High severity · published Aug 19, 2026
CVE-2026-18821
Power System Out-of-bounds Write
8.8
CVSS
0.3%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 21% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PH
PowerVM Hypervisor · IBM
FW1120.00; FW1110.00 through FW1110.30; FW1060.00 through FW1060.80; FW950.00 through FW950.H2 · source: vendor
PS
Power System E1050 (9043-mrx) Firmware · Ibm
fw1060.00 before fw1060.81 · source: NVD
PS
Power System E1080 (9080-hex) Firmware · Ibm
fw1060.00 before fw1060.81 · source: NVD
PS
Power System E1150 (9043-mru) Firmware · Ibm
fw1110.00 before fw1110.31; fw1120.00 · source: NVD
PS
Power System E1180 (9080-heu) Firmware · Ibm
fw1110.00 before fw1110.31; fw1120.00 · source: NVD
PS
Power System E950 (9040-mr9) Firmware · Ibm
fw950.00 before fw950.h3 · source: NVD
PS
Power System E980 (9080-m9s) Firmware · Ibm
fw950.00 before fw950.h3 · source: NVD
PS
Power System H922 (9223-22s) Firmware · Ibm
fw950.00 before fw950.h3 · source: NVD
PS
Power System H924 (9223-42s) Firmware · Ibm
fw950.00 before fw950.h3 · source: NVD
PS
Power System L1022 (9786-22h) Firmware · Ibm
fw1060.00 before fw1060.81 · source: NVD
PS
Power System L1024 (9786-42h) Firmware · Ibm
fw1060.00 before fw1060.81 · source: NVD
PS
Power System L1122 (9856-22h) Firmware · Ibm
fw1110.00 before fw1110.31; fw1120.00 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-18821
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-18821
Vendor Advisory
https://www.ibm.com/support/pages/node/7283232
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