CVE-2026-95696 in WebSphere Application Server
Summary
by MITRE • 10/15/2026
IBM WebSphere Application Server - Liberty 20.0.0.12 through 26.0.0.10 could allow a remote attacker to cause a denial of service due to an uncaught exception.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in IBM WebSphere Application Server Liberty versions ranging from 20.0.0.12 through 26.0.0.10 represents a critical reliability issue stemming from improper error handling within the application server runtime environment. This flaw allows an unauthenticated or authenticated remote attacker to trigger a denial of service condition by exploiting an uncaught exception that occurs during request processing. The root cause lies in the failure of specific components within the Liberty profile to properly validate input parameters or handle edge cases, leading to a state where the Java Virtual Machine encounters an unrecoverable error rather than gracefully managing the anomalous data. This lack of robust exception handling means that instead of returning a standard HTTP error code such as 400 Bad Request, the server process may crash or become unresponsive, effectively halting service delivery for all users attempting to access applications hosted on this instance.
From a technical perspective, this vulnerability aligns with CWE-253, which describes an incorrect check for an unusual condition, and more specifically relates to CWE-754, the improper check for uncommon or exceptional conditions. When a remote attacker sends specially crafted HTTP requests containing malformed headers, unexpected data structures, or specific sequences designed to trigger internal logic errors within the Liberty runtime, the application server fails to catch these exceptions at the appropriate layer of the stack trace. Consequently, the thread handling the request terminates abruptly without cleanup procedures being executed properly. In many cases involving Java-based enterprise servers, such uncaught exceptions can lead to thread pool exhaustion or complete JVM crashes depending on how the exception propagates through the servlet container and underlying libraries. This behavior transforms what might otherwise be a simple client-side error into a server-side stability issue with significant operational consequences.
The operational impact of this vulnerability is primarily centered around availability, which constitutes one of the three pillars of information security alongside confidentiality and integrity. By successfully exploiting this flaw, an attacker can disrupt business operations by rendering the IBM WebSphere Application Server Liberty instance unavailable to legitimate users. This denial of service does not necessarily require complex exploitation techniques or prior authentication in all scenarios, making it a low-effort attack vector for malicious actors seeking to cause disruption. The persistence of the issue depends on whether the server automatically restarts after crashing; however, even with auto-restart mechanisms in place, repeated attacks can lead to resource exhaustion during recovery phases, causing prolonged downtime and potential data inconsistency if transactions were mid-flight when the crash occurred. This directly impacts service level agreements and organizational reputation by demonstrating a lack of resilience against basic network-based disruptions.
To mitigate this risk, organizations running affected versions of IBM WebSphere Application Server Liberty must apply the latest security patches provided by IBM that address these specific exception handling flaws. It is imperative to upgrade beyond version 26.0.0.10 or ensure that any interim fixes released for earlier versions in the supported range are installed promptly. In addition to patching, defense-in-depth strategies should be employed, including placing a Web Application Firewall in front of the Liberty instances to filter out malformed requests before they reach the application server logic. Network segmentation can also help limit exposure by restricting access to administrative interfaces and sensitive endpoints only from trusted IP ranges. Furthermore, developers integrating with or extending this platform should implement rigorous input validation and ensure that all external-facing code paths include comprehensive try-catch blocks designed to handle unexpected inputs gracefully without propagating exceptions up the stack in a manner that could destabilize the runtime environment. Regular vulnerability scanning and penetration testing focused on error handling weaknesses will help identify similar issues before they can be exploited in production environments, ensuring higher overall system resilience against denial of service attacks categorized under MITRE ATT&CK technique T1499, Endpoint Denial of Service.