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CVE-2026-18871NVD status: Analyzed

PowerVM Hypervisor: Stack-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2026-18871 is a high-severity stack-based buffer overflow vulnerability in PowerVM Hypervisor from IBM, with a CVSS 3.1 base score of 7.3 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected PowerVM Hypervisor versions: FW1120.00; FW1110.00 through FW1110.30; FW1060.00 through FW1060.80. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Power System S1122 (9824-22a) Firmware to fw1110.31 or a later version.
  2. Update Power System S1124 (9824-42a) Firmware to fw1110.31 or a later version.
  3. Update Power System S1122s (9824-22b) Firmware to fw1110.31 or a later version.
  4. Read the advisory on ibm.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
IBMPowerVM HypervisorFW1120.00; FW1110.00 through FW1110.30; FW1060.00 through FW1060.80Not stated
IBMPower System S1122 (9824-22a) Firmwarefw1110.00 up to, but not including, fw1110.31; fw1120.00fw1110.31
IBMPower System S1124 (9824-42a) Firmwarefw1110.00 up to, but not including, fw1110.31; fw1120.00fw1110.31
IBMPower System S1122s (9824-22b) Firmwarefw1110.00 up to, but not including, fw1110.31; fw1120.00fw1110.31
IBMPower System S1114 (9824-41b) Firmwarefw1110.00 up to, but not including, fw1110.31; fw1120.00fw1110.31
IBMPower System L1122 (9856-22h) Firmwarefw1110.00 up to, but not including, fw1110.31; fw1120.00fw1110.31
IBMPower System L1124 (9856-42h) Firmwarefw1110.00 up to, but not including, fw1110.31; fw1120.00fw1110.31
IBMPower System E1150 (9043-mru) Firmwarefw1110.00 up to, but not including, fw1110.31; fw1120.00fw1110.31
IBMPower System S1112 (9242-21b) Firmwarefw1120.00Not stated
IBMPower System S1112 (9242-21t) Firmwarefw1120.00Not stated
IBMPower System E1080 (9080-hex) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System S1022 (9105-22a) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System S1024 (9105-42a) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System S1022s (9105-22b) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System S1014 (9105-41b) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System L1022 (9786-22h) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System L1024 (9786-42h) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System E1050 (9043-mrx) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System S1012 (9028-21b) Firmwarefw1060.00 up to, but not including, fw1060.81fw1060.81
IBMPower System E1180 (9080-heu) Firmwarefw1110.00 up to, but not including, fw1110.31; fw1120.00fw1110.31

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
NoneNo data is disclosed.
Integrity
LowLimited modification of data is possible.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:H. Scored by CNA (us.ibm.com).

Official description

IBM PowerVM Hypervisor FW1120.00, FW1110.00 through FW1110.30, and FW1060.00 through FW1060.80 is affected by a vulnerability in host firmware configuration parsing. An attacker with authenticated service-level access to the service processor can write specially crafted configuration data, causing the host firmware boot stack to crash with possible memory corruption during system initialisation, resulting in an integrity and availability impact to the managed system.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Stack-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the stack.

How developers prevent this class of flaw

  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Implement and perform bounds checking on input.

More Stack-based Buffer Overflow vulnerabilities (CWE-121)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in PowerVM Hypervisor

All PowerVM Hypervisor vulnerabilities

Recent Stack-based Buffer Overflow vulnerabilities

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