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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 PowerVM hypervisor call interface. An attacker with root access to a guest partition can issue a specially crafted hypervisor call to inject an arbitrary amount of data into hypervisor or partition memory, resulting in either a crash causing a full platform re-IPL and terminating all hosted partitions, or corruption of hypervisor or partition memory. The PowerVM hypervisor will restart automatically; however, repeated exploitation could result in a sustained availability impact. Successful exploitation results in an integrity and availability impact to the managed system.
This vulnerability originates from an integer overflow in the PowerVM hypervisor call interface. The core technical issue lies in the improper validation or handling of specific hypercalls, which are system calls used by operating systems to request services from the hypervisor. When these malformed requests are processed, they trigger an internal state corruption within the PowerVM environment rather than being safely rejected or handled gracefully. This lack of robust input sanitization at the boundary between guest OS and hypervisor constitutes a significant breach in virtualization security principles, allowing lateral movement from a compromised user-space application to critical infrastructure components. The attack requires root access in a guest, meaning privilege escalation within a virtual machine is a prerequisite. Once achieved, the attacker can trigger a crash or memory corruption, leading to loss of service or compromise of data integrity. Upon exploitation, the attack causes a specific virtual processor within the managed hardware partition to become permanently unresponsive or injects arbitrary data into hypervisor or partition memory. Restoring normal operation requires a full platform re-IPL (Initial Program Load), which is equivalent to a hard reboot of the entire physical server. This requirement introduces substantial downtime and operational disruption, as all partitions running on that hardware must be restarted manually by an administrator or automated recovery system. The necessity for such a drastic measure underscores the severity of the internal state corruption caused by the malicious hypercall, highlighting how guest-level actions can destabilize the foundational infrastructure layer. From a classification perspective, this vulnerability aligns with CWE-190: Integer Overflow or Wraparound, as it involves improper handling of integer calculations leading to memory corruption.
DailyCVE Form:
Platform: IBM PowerVM Hypervisor
Version: FW950-FW1120
Vulnerability: Integer Overflow
Severity: High (8.4)
date: 2026-08-19
Prediction: 2026-08-25 (FW1060.81/FW1110.31)
What Undercode Say:
Check current PowerVM firmware version lsmcode -c Check for CVE-2026-17091 in IBM security bulletins curl -s https://www.ibm.com/support/pages/node/7283231 | grep -i "CVE-2026-17091" Verify if the system is running an affected firmware version Affected: FW1120.00, FW1110.00-FW1110.30, FW1060.00-FW1060.80, FW950.00-FW950.H2 uname -a | grep -E "FW1120|FW1110|FW1060|FW950"
Exploit: (Educational Purposes!)
Craft a malicious hypercall with oversized parameters to trigger integer overflow This is a conceptual example - actual exploit code is not provided The overflow causes either a crash (re-IPL) or memory corruption Requires root access within a guest partition Example: hcall(SET_PARM, 0xFFFFFFFF, 0xFFFFFFFF, ...)
Protection:
Install FW1110.31(1110_134), FW1120.01(1120_167), or newer for Power 11 systems. Install FW1060.81(1060_184), or newer for Power 10 systems. Restrict root access to guest partitions and monitor for unusual hypervisor call patterns.
Impact:
Full platform re-IPL terminating all hosted partitions, corruption of hypervisor or partition memory, sustained availability impact with repeated exploitation, integrity and availability impact to the managed system.
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Sources:
Reported By: nvd.nist.gov
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