CVE-2026-18871 in PowerVM Hypervisor
Summary
by MITRE • 08/19/2026
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.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/19/2026
The IBM PowerVM Hypervisor versions FW1120.00, FW1110.00 through FW1110.30, and FW1060.00 through FW1060.80 are susceptible to a critical vulnerability stemming from insufficient validation during the parsing of host firmware configuration data. This flaw resides within the service processor's handling of administrative inputs, specifically targeting the mechanisms responsible for initializing system parameters at boot time. The security issue is classified under CWE-20 as Improper Input Validation, where the software fails to adequately verify or sanitize user-supplied input before processing it. In this specific context, the configuration data written by an administrator is not rigorously checked against expected formats, lengths, or logical constraints, allowing malformed or specially crafted payloads to bypass standard validation routines and enter deeper system layers during initialization.
An attacker possessing authenticated service-level access to the service processor can exploit this weakness by injecting maliciously constructed configuration parameters into the firmware update or management interface. Because the vulnerability occurs during the host firmware boot stack processing phase, the impact is immediate upon system restart or reconfiguration attempts. The execution of these crafted inputs leads to a crash in the host firmware boot sequence. More critically, the parsing error can result in memory corruption within the hypervisor's operational environment. This type of flaw aligns with CWE-120 Buffer Overflow and potentially CWE-787 Out-of-bounds Write, as improper handling of configuration strings or binary data structures may overwrite adjacent memory regions that are critical for system stability and security control functions.
The operational impact of this vulnerability is severe, affecting both the integrity and availability of the managed Power Systems environment. The immediate consequence is a denial of service condition caused by the crash of the host firmware boot stack, which prevents the operating systems hosted on the partition from loading correctly. This results in significant downtime for critical workloads running on IBM PowerVM infrastructure. Beyond simple unavailability, the potential for memory corruption introduces risks to data integrity and system stability. If an attacker can control the content written during this phase, they may potentially manipulate low-level firmware behaviors or disrupt security boundaries between partitions, although the primary documented impact remains focused on availability through crash conditions and potential instability due to corrupted memory states.
From a threat modeling perspective, this vulnerability represents a significant risk for environments where service processor access is granted to multiple administrative roles without strict segregation of duties. It maps to MITRE ATT&CK technique T1531 Accessing Cloud Infrastructure Accounts if the service processor is considered part of the cloud management plane, or more accurately to local privilege escalation vectors within the hardware abstraction layer. The attack vector requires authentication, which limits its exploitability by remote unauthenticated actors but makes it highly dangerous for insider threats or compromised administrative accounts that have been granted elevated privileges on the service processor interface.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. IBM has released firmware updates to address this issue, and administrators should apply the latest available patches for their specific PowerVM version immediately after verifying compatibility with existing workloads. In addition to patching, organizations should enforce strict access controls on service processor interfaces, ensuring that only a minimal set of trusted personnel have write-access capabilities. Implementing multi-factor authentication for service console access and auditing all configuration changes can help detect unauthorized attempts to exploit this flaw before they result in system crashes. Furthermore, adopting a principle of least privilege ensures that even if an account is compromised, the attacker lacks the necessary permissions to modify critical firmware configurations during boot sequences. Regular vulnerability scanning and penetration testing focused on management interfaces are recommended to identify similar input validation weaknesses across the infrastructure.