CVE-2025-36250 Overview
IBM AIX 7.2, 7.3, and IBM VIOS 3.1, 4.1 are affected by a critical remote command execution vulnerability in the NIM server (formerly known as NIM master) service (nimesis). This vulnerability allows a remote attacker to execute arbitrary commands due to improper process controls. Notably, this CVE addresses additional attack vectors for a vulnerability that was previously patched in CVE-2024-56346, indicating that the initial remediation was incomplete.
Critical Impact
Unauthenticated remote attackers can execute arbitrary commands on affected IBM AIX and VIOS systems running the NIM server service, potentially leading to complete system compromise.
Affected Products
- IBM AIX 7.2
- IBM AIX 7.3
- IBM VIOS 3.1
- IBM VIOS 4.1
Discovery Timeline
- 2025-11-13 - CVE-2025-36250 published to NVD
- 2025-11-19 - Last updated in NVD database
Technical Details for CVE-2025-36250
Vulnerability Analysis
This vulnerability is classified under CWE-114 (Process Control), which occurs when an application does not properly manage processes or allows external influence over process behavior. The NIM server (nimesis) service in IBM AIX and VIOS fails to properly validate and control process execution, enabling remote attackers to inject and execute arbitrary commands on the target system.
The network-accessible nature of the NIM service, combined with the lack of required authentication or user interaction for exploitation, makes this vulnerability particularly dangerous in enterprise environments where NIM servers manage multiple AIX and VIOS clients.
Root Cause
The root cause lies in improper process controls within the nimesis service. The NIM server architecture allows remote management of AIX and VIOS installations, updates, and configurations. However, insufficient validation of input destined for process execution paths enables command injection. This vulnerability represents a bypass of the previous fix implemented for CVE-2024-56346, suggesting that additional code paths or edge cases were not adequately addressed in the original remediation.
Attack Vector
The vulnerability is exploitable remotely over the network. An attacker does not require any privileges or authentication to exploit this flaw, nor is any user interaction necessary. The nimesis service typically listens on network ports to facilitate NIM operations across managed systems. By sending specially crafted requests to the NIM server, an attacker can manipulate process controls to execute arbitrary commands with the privileges of the nimesis service, which typically runs with elevated permissions.
The exploitation flow involves:
- Identifying an exposed NIM server (nimesis service)
- Crafting malicious requests that exploit the improper process control mechanism
- Injecting commands that bypass the previous CVE-2024-56346 mitigations
- Achieving arbitrary command execution on the target AIX/VIOS system
Detection Methods for CVE-2025-36250
Indicators of Compromise
- Unexpected processes spawned as children of the nimesis service
- Anomalous network connections originating from or destined to the NIM server on non-standard ports
- Unusual command execution patterns in system logs associated with NIM operations
- Modifications to system files or configurations outside of scheduled NIM activities
Detection Strategies
- Monitor process creation events associated with the nimesis service for unexpected child processes or command execution
- Implement network monitoring to detect unusual traffic patterns to NIM server ports
- Analyze authentication logs and NIM service logs for signs of unauthorized access attempts
- Deploy endpoint detection solutions capable of identifying command injection attack patterns
Monitoring Recommendations
- Configure audit logging on AIX and VIOS systems to capture all process execution events related to NIM services
- Implement network segmentation and monitor traffic to NIM servers from untrusted network segments
- Establish baseline behavior for NIM operations and alert on deviations
- Review IBM AIX and VIOS security bulletins regularly for updates related to this and related vulnerabilities
How to Mitigate CVE-2025-36250
Immediate Actions Required
- Apply the security patch provided by IBM immediately to all affected AIX and VIOS systems
- Restrict network access to NIM server services to only authorized management networks
- If patching cannot be performed immediately, consider disabling the nimesis service on systems where it is not actively required
- Audit systems for signs of prior exploitation before and after patching
Patch Information
IBM has released security updates to address this vulnerability. Administrators should obtain and apply the appropriate patches from the IBM Support Page. Organizations that previously patched for CVE-2024-56346 must apply this additional update, as the earlier fix did not address all attack vectors.
Workarounds
- Implement network-level access controls (firewalls, ACLs) to restrict access to NIM server ports from untrusted networks
- Disable the nimesis service on systems where NIM server functionality is not required
- Deploy network intrusion detection/prevention systems to monitor and block suspicious traffic to NIM services
- Consider placing NIM servers in isolated management VLANs with strict access controls
# Example: Restrict nimesis service access using AIX TCP Wrappers
# Add to /etc/hosts.allow
nimesis: 192.168.10.0/255.255.255.0
# Add to /etc/hosts.deny
nimesis: ALL
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
