Description

IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 NIM server process is crashing during client registration due to buffer overflow.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-08-19T15:16:55.427Z",
  "pubdate": "2026-08-19T15:16:55.427Z",
  "executiveSummary": "A buffer overflow vulnerability exists within the Network Installation Management (NIM) server process in IBM AIX 7.2, 7.3, and IBM PowerVM VIOS 4.1. The vulnerability is triggered specifically during the client registration process, where improper bounds checking allows untrusted input to corrupt adjacent memory regions within the server process address space. Exploitation of this security flaw results in the crashing of the NIM server process, leading to a denial of service condition that disrupts central operating system installation, configuration, and management operations across the enterprise environment. The risk implication involves the potential disruption of administrative infrastructure and availability loss of the NIM service. Attackers capable of interacting with the NIM server during client registration can trigger the crash. Based on the provided description, specific exploitation requirements center around initiating a crafted client registration sequence that overflows the vulnerable input buffer within the NIM server daemon or associated sub-processes.",
  "technicalDetails": "The vulnerability resides in the Network Installation Management (NIM) server process utilized across IBM AIX 7.2, IBM AIX 7.3, and IBM PowerVM VIOS 4.1. The root cause of the flaw is a classic buffer overflow condition, stemming from insufficient validation and bounds checking on data supplied during the client registration procedure. When a client initiates communication or registration with the NIM master server, the server process allocates a fixed-size buffer to ingest incoming registration parameters or network streams. If the length of the incoming data exceeds the allocated capacity of the buffer without proper truncation or input filtering, a memory overwrite occurs.\nThe attack flow begins with the malicious or malformed input being transmitted across the network protocol used by NIM client registration. As the NIM server process parses and copies the input data into the vulnerable buffer, the overflow overwrites adjacent stack or heap structures, including control data, return addresses, or internal application state variables. This memory corruption disrupts the normal execution flow of the server process, causing an immediate segmentation fault or unhandled exception that forces the process to crash.\nRegarding environmental context, the vulnerable component is the NIM server daemon responsible for handling administrative registrations. The affected versions include IBM AIX 7.2, IBM AIX 7.3, and IBM PowerVM VIOS 4.1. Network exposure is tied to the listening ports utilized by the NIM service. Depending on the operational configuration, this may require network connectivity to the NIM master server. The post-exploitation impact described is primarily a denial of service via process termination, preventing administrators from successfully registering new clients or managing existing NIM operations until the service is manually or automatically restarted. Authentication and privilege requirements depend on whether unauthenticated clients can initiate registration sequences or if the environment restricts registration tasks to pre-configured master-client trust relationships."
}