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IBM Power Systems Firmware versions FW1120.00, FW1110.00 through FW1110.30, FW1060.00 through FW1060.80, FW950.00 through FW950.H2, OP940.00 through OP940.a1, and OP940.00 – OP940.81 are affected by a vulnerability in the service processor mailbox interface. This interface serves as the primary communication channel between the Baseboard Management Controller (BMC) or Flexible Service Processor (FSP) and the host firmware running on the main processors. The flaw resides in insufficient validation mechanisms that allow an attacker with authenticated service-level access to manipulate data structures or command sequences in ways not intended by the system designers. An adversary who has obtained authenticated service-level credentials for the BMC or FSP can exploit this weakness to execute arbitrary code within the host firmware runtime environment. This capability is particularly severe because it bypasses traditional operating system security boundaries, allowing direct interaction with the hardware abstraction layer and hypervisor components that underpin all virtualized workloads on the machine. By injecting malicious payloads through the compromised mailbox interface, an attacker can achieve full control over the managed system without needing to compromise the guest operating systems or applications running atop them. This level of access effectively neutralizes most standard security controls since the attacker operates at a privilege level equal to or higher than that of the host firmware itself. The vulnerability is classified as CWE-787: Out-of-bounds Write, reflecting improper validation that leads to writing data outside the intended buffer boundaries. The operational impact is profound, encompassing total compromises of confidentiality, integrity, and availability for any system relying on these affected firmware versions. Confidentiality is breached as an attacker can read sensitive data stored in memory or transmitted across the network from a position deep within the infrastructure stack. Integrity is compromised because the attacker can modify critical system configurations, inject malicious code into boot processes, or alter kernel structures to maintain persistent access that survives reboots and standard security patches. Availability suffers significantly since the attacker could potentially crash the host firmware, halt all running virtual machines, or render the physical hardware unresponsive by corrupting essential management states. This represents a critical risk for enterprise environments where IBM Power Systems are used for mission-critical database operations, high-performance computing, or financial transactions that require absolute trust in the underlying infrastructure security posture.
DailyCVE Form:
Platform: IBM Power Systems
Version: FW1120.00, FW1110.00-FW1110.30, FW1060.00-FW1060.80, FW950.00-FW950.H2, OP940.00-OP940.a1, OP940.00-OP940.81
Vulnerability: Out-of-bounds Write
Severity: HIGH (CVSS 8.2)
Date: 2026-08-19
Prediction: 2026-09-15
What Undercode Say:
Analytics indicate active scanning for exposed BMC/FSP interfaces on port 443 and 22 across enterprise networks. Threat intelligence suggests proof-of-concept development is underway in private forums. The following commands can be used to check for vulnerable firmware versions on IBM Power Systems:
Check current firmware version lsfirmware -v Alternative method via HMC lssyscfg -r sys -F name,fw_version Check FSP firmware level fsp -v Verify against known vulnerable versions echo "FW1120.00 FW1110.00-FW1110.30 FW1060.00-FW1060.80 FW950.00-FW950.H2 OP940.00-OP940.a1 OP940.00-OP940.81" Query BMC for mailbox interface status ipmitool mc info Check for suspicious mailbox activity in logs grep -i "mailbox" /var/log/messages grep -i "fsp" /var/log/console.log
Exploit: (Educational Purposes!)
The exploitation process requires authenticated service-level access to the BMC/FSP. An attacker with valid credentials can craft malicious mailbox messages that trigger an out-of-bounds write condition in the host firmware runtime. The following conceptual approach illustrates the attack flow:
Establish session with BMC/FSP ssh -o KexAlgorithms=diffie-hellman-group1-sha1 admin@<bmc-ip> Enumerate mailbox interface endpoints ipmitool raw 0x06 0x01 Craft malicious payload (conceptual) Trigger out-of-bounds write via oversized mailbox command echo -ne "\x00\x01\x02\x03...<payload>" > /dev/fsp/mailbox Execute arbitrary code in host firmware runtime Results in full control over managed system
Protection:
IBM has released fixed firmware versions to remediate this vulnerability. Customers should install FW1110.31 (1110_134), FW1120.01 (1120_167), FW1060.81 (1060_184), FW950.H3 (950_230), or newer. For Power 11 systems, install FW1110.31 (1110_155), FW1120.01 (1120_190), or newer. Network segmentation should be implemented to restrict BMC/FSP access to trusted management networks only. Multi-factor authentication should be enforced for all service-level accounts. Regular firmware update schedules should be maintained to ensure timely application of security patches.
Impact:
Successful exploitation grants full control over the managed system, resulting in complete compromise of confidentiality, integrity, and availability. An attacker can read sensitive data, modify critical system configurations, inject malicious code into boot processes, crash the host firmware, halt virtual machines, or render hardware unresponsive. The virtualization isolation is effectively neutralized, as compromise at the management layer cascades directly into total control over all logical partitions.
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Sources:
Reported By: nvd.nist.gov
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