CVE-2026-9002
Summary
by MITRE • 06/30/2026
IBM WebSphere Extreme Scale 8.6.1.0 through 8.6.1.6 could allow an adjacent attacker to cause a denial of service due to improper validation in the XDF decoder. The application processes deeply nested Protocol Buffers messages and attacker-controlled length prefixes without sufficient bounds checking, which may allow an attacker on the same network to trigger a StackOverflowError or OutOfMemoryError, resulting in a crash of the WebSphere Application Server JVM.
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Analysis
by VulDB Data Team • 06/30/2026
IBM WebSphere Extreme Scale versions 8.6.1.0 through 8.6.1.6 contains a critical denial of service vulnerability stemming from inadequate input validation within the XDF decoder component. This flaw specifically affects the processing of Protocol Buffers messages where attacker-controlled length prefixes are not properly bounded, creating a path for malicious actors to manipulate the application's memory management behavior. The vulnerability exists at the protocol parsing layer where the system fails to implement sufficient bounds checking mechanisms when handling nested message structures, allowing an adjacent network attacker to craft specially malformed data packets that exploit this weakness.
The technical execution of this vulnerability relies on the application's failure to validate the length fields within Protocol Buffers messages before attempting to parse nested structures. When processing these attacker-controlled inputs, the system performs recursive parsing operations without adequate stack depth or memory allocation limits, which directly maps to CWE-129 Input Validation and CWE-770 Allocation of Resources Without Limits or Throttling. The absence of proper bounds checking creates a condition where deeply nested message structures can cause the Java Virtual Machine to exhaust available stack space leading to StackOverflowError or consume excessive heap memory resulting in OutOfMemoryError, both of which terminate the WebSphere Application Server JVM process.
The operational impact of this vulnerability extends beyond simple service interruption as it represents a significant threat vector for network-based attackers who have access to the same broadcast domain as the target system. Attackers can leverage this weakness to perform persistent denial of service attacks against critical business applications that depend on WebSphere Extreme Scale for data management and caching operations. The vulnerability's exploitation requires only network connectivity to the affected server, making it particularly dangerous in environments where internal network segmentation is not properly implemented or where attackers have gained access to shared network segments. This attack pattern aligns with ATT&CK technique T1499.004 Network Denial of Service and represents a common vector for persistent service disruption attacks.
Organizations should implement immediate mitigations including applying the latest security patches from IBM, implementing network segmentation to isolate WebSphere Extreme Scale instances, and configuring proper input validation at network boundaries. Additional defensive measures include deploying intrusion detection systems to monitor for suspicious Protocol Buffers traffic patterns and implementing application-level rate limiting to prevent abuse of the vulnerable parsing functionality. The vulnerability demonstrates the critical importance of robust input validation in network-facing applications and highlights the need for comprehensive security testing of protocol parsers, particularly those handling structured data formats like Protocol Buffers that are commonly used in high-performance distributed systems.