IBM PowerVM Hypervisor FW1110.00-1110.30 Service Processor Mailbox RCE
CVE-2026-16661 Published on August 19, 2026
Power System Integer Overflow
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 service processor mailbox interface. An attacker with authenticated service-level access to the FSP can exploit this vulnerability, allowing arbitrary code to be executed in the host firmware runtime, giving full control over the managed system, resulting in a confidentiality, integrity, and availability impact to the managed system.
Vulnerability Analysis
CVE-2026-16661 can be exploited with local system access, and requires user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Type
Integer Overflow or Wraparound
The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control. An integer overflow or wraparound occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may wrap to become a very small or negative number. While this may be intended behavior in circumstances that rely on wrapping, it can have security consequences if the wrap is unexpected. This is especially the case if the integer overflow can be triggered using user-supplied inputs. This becomes security-critical when the result is used to control looping, make a security decision, or determine the offset or size in behaviors such as memory allocation, copying, concatenation, etc.
Products Associated with CVE-2026-16661
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Affected Versions
IBM PowerVM Hypervisor:- Version FW1120.00 is affected.
- Version FW1110.00, <= FW1110.30 is affected.
- Version FW1060.00, <= FW1060.80 is affected.
- Version FW950.00, <= FW950.H2 is affected.