CVE-2001-0122 in WebSphere Application Server
Summary
by MITRE
Kernel leak in AfpaCache module of the Fast Response Cache Accelerator (FRCA) component of IBM HTTP Server 1.3.x and Websphere 3.52 allows remote attackers to cause a denial of service via a series of malformed HTTP requests that generate a "bad request" error.
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Analysis
by VulDB Data Team • 10/08/2025
The vulnerability identified as CVE-2001-0122 represents a critical kernel memory leak within the AfpaCache module of IBM's Fast Response Cache Accelerator FRCA component. This flaw exists in IBM HTTP Server versions 1.3.x and WebSphere 3.52, where the kernel memory management becomes compromised when processing malformed HTTP requests. The vulnerability operates through a specific pattern of request manipulation that triggers an improper error handling mechanism, ultimately leading to memory exhaustion and system instability. The flaw demonstrates a fundamental weakness in how the system manages memory allocation during error processing, creating a pathway for malicious actors to exploit the underlying kernel structures.
The technical implementation of this vulnerability involves the AfpaCache module's failure to properly handle malformed HTTP requests that generate "bad request" error responses. When these specific malformed requests are processed, the module enters a state where kernel memory allocated for cache operations is not properly released back to the system. This memory leak occurs repeatedly with each malicious request, gradually consuming available kernel memory resources until the system becomes unresponsive or crashes entirely. The vulnerability is classified under CWE-401 as a failure to release memory resources, specifically manifesting as a memory leak in kernel space. The attack vector requires only remote access to send specially crafted HTTP requests that exploit the module's inadequate error handling procedures.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it represents a significant threat to system availability and stability within enterprise web infrastructure. Organizations running affected versions of IBM HTTP Server and WebSphere are particularly at risk since the vulnerability can be exploited without authentication, allowing attackers to systematically degrade system performance through repeated memory consumption. The cumulative effect of these memory leaks can lead to complete system crashes, requiring manual intervention and system restarts to restore normal operations. This vulnerability directly maps to ATT&CK technique T1499.004 for network denial of service attacks, where adversaries leverage system resource exhaustion to disrupt services.
Mitigation strategies for this vulnerability require immediate patching of affected systems with the appropriate security updates provided by IBM. Organizations should implement network segmentation to limit access to affected servers and deploy intrusion detection systems to monitor for suspicious HTTP request patterns that may indicate exploitation attempts. Additionally, configuring the FRCA module to limit the number of concurrent connections and implementing rate limiting mechanisms can help reduce the impact of potential attacks. System administrators should also establish monitoring protocols to track memory usage patterns and implement automated alerts when memory consumption exceeds normal thresholds, allowing for proactive intervention before complete system failure occurs. The vulnerability demonstrates the critical importance of proper memory management in kernel modules and highlights the need for comprehensive security testing of caching and acceleration components within enterprise web infrastructure.