CVE-2026-16868 in IBM
Summary
by MITRE • 08/13/2026
IBM i 7.6, 7.5, 7.4, and 7.3 could allow a remote attacker to cause a denial of service due to the use of uninitialized memory during ASN.1 length processing.
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Analysis
by VulDB Data Team • 08/13/2026
This vulnerability exists within IBM i operating systems versions 7.6, 7.5, 7.4, and 7.3 where an uninitialized memory access occurs during ASN.1 length processing operations. The flaw represents a classic buffer over-read condition that can be exploited remotely to disrupt system availability. When the system processes ASN.1 encoded data structures for length determination, it fails to properly initialize memory variables before use, creating opportunities for malicious actors to craft specially formatted inputs that trigger the vulnerability.
The technical implementation of this issue stems from improper memory management during cryptographic protocol handling and data parsing operations. ASN.1 (Abstract Syntax Notation One) is a standard encoding method widely used in security protocols including SSL/TLS, X.509 certificates, and various network protocols. When processing these structures, the system's ASN.1 parser encounters uninitialized memory locations that contain residual data from previous operations, leading to unpredictable behavior during length calculations. This vulnerability aligns with CWE-457: Use of Uninitialized Variable, which specifically addresses scenarios where programs use variables without proper initialization.
The operational impact of this vulnerability extends beyond simple denial of service conditions. Remote attackers can leverage this weakness to cause system instability through repeated exploitation attempts, potentially leading to complete system crashes or forced reboots. The nature of the flaw suggests it may be exploitable in various network services that process ASN.1 encoded data, including but not limited to secure shell implementations, certificate management systems, and cryptographic service providers. This represents a significant threat to business continuity as the vulnerability affects multiple major versions of IBM i operating system, creating widespread exposure across enterprise environments.
From an adversary perspective, this vulnerability fits within the ATT&CK framework under T1499.004: Endpoint Denial of Service, specifically targeting system resources through memory corruption techniques. The remote exploitation capability means that attackers need not have physical access or local credentials to cause disruption. Organizations should implement immediate mitigations including applying the relevant IBM security patches and updates, implementing network segmentation to limit exposure, and monitoring for unusual system behavior or connection patterns. Additionally, configuring intrusion detection systems to identify potential exploitation attempts targeting ASN.1 parsing functions would provide early warning capabilities. The vulnerability demonstrates the critical importance of proper memory initialization practices in security-critical code sections, particularly within cryptographic processing components where uninitialized memory access can have severe operational consequences.