CVE-2026-1376 in IBM
Summary
by MITRE • 03/18/2026
IBM i 7.6 could allow a remote attacker to cause a denial of service using failed authentication connections due to improper allocation of resources.
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Analysis
by VulDB Data Team • 03/21/2026
IBM i 7.6 contains a vulnerability that enables remote attackers to trigger a denial of service condition through malformed authentication attempts. This flaw stems from inadequate resource management during failed connection sequences, where the system fails to properly release allocated memory and processing resources when authentication requests are rejected. The vulnerability manifests when multiple concurrent failed authentication attempts are made against the system, leading to progressive resource exhaustion that eventually renders the system unavailable to legitimate users. This issue represents a classic resource exhaustion attack vector that aligns with common attack patterns documented in the attack mitigation framework.
The technical root cause of this vulnerability lies in the system's handling of authentication failure states within its network services framework. When authentication requests fail, the IBM i 7.6 operating system does not properly implement resource cleanup routines that would normally occur during successful connection establishment or termination. This improper allocation and subsequent failure to deallocate system resources creates a memory leak condition that accumulates over time. The vulnerability is particularly concerning because it operates at the system level where network services are managed, making it difficult to distinguish between legitimate and malicious connection attempts without proper monitoring mechanisms in place.
From an operational impact perspective, this vulnerability can severely disrupt business continuity for organizations relying on IBM i 7.6 systems. The denial of service condition can affect critical applications that depend on authentication services, potentially causing cascading failures throughout the enterprise infrastructure. System administrators may observe gradual performance degradation before complete service unavailability, making early detection challenging. The vulnerability affects multiple network protocols including but not limited to ftp telnet and ssh services that utilize the affected authentication mechanisms. Organizations with high connection volumes or those operating in regulated environments may face compliance violations if service availability is compromised, as this vulnerability directly impacts the availability aspect of the CIA triad.
The vulnerability has been classified under CWE-400 as a resource exhaustion weakness, specifically related to improper resource management during error handling scenarios. It also aligns with ATT&CK technique T1499.004 which covers network denial of service attacks, and T1566.002 which involves social engineering through phishing or other means that could be used to amplify the attack vectors. Organizations should implement connection rate limiting mechanisms and establish monitoring protocols to detect unusual authentication failure patterns that could indicate exploitation attempts. Network segmentation and firewall rules can help limit the impact by restricting access to critical authentication services from untrusted networks, while proper logging and alerting configurations should be enabled to detect resource exhaustion patterns before complete service disruption occurs.
Recommended mitigations include applying the vendor-provided security patches immediately, implementing connection throttling policies that limit failed authentication attempts per source IP address, and configuring system monitoring to track resource utilization patterns. System administrators should also consider implementing intrusion detection systems that can identify suspicious authentication patterns and automatically trigger alerts or blocking mechanisms. Regular security assessments should be conducted to ensure that authentication services are properly configured and that resource management policies are effectively enforced. The vulnerability demonstrates the importance of robust error handling and resource management in system design, particularly for critical infrastructure components that must maintain availability under all conditions. Organizations should also review their incident response procedures to ensure they can effectively respond to denial of service conditions that may arise from such vulnerabilities, maintaining business continuity during potential exploitation attempts.