CVE-2000-0897 in Small HTTP Server
Summary
by MITRE
Small HTTP Server 2.03 and earlier allows remote attackers to cause a denial of service by repeatedly requesting a URL that references a directory that does not contain an index.html file, which consumes memory that is not released after the request is completed.
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Analysis
by VulDB Data Team • 03/14/2025
The vulnerability described in CVE-2000-0897 represents a classic memory management flaw in web server implementations that can be exploited to achieve denial of service conditions. This issue affects Small HTTP Server version 2.03 and earlier, demonstrating how seemingly minor implementation oversights can create significant security risks. The vulnerability specifically targets the server's handling of directory requests where index files are absent, creating a memory consumption pattern that persists across multiple requests.
The technical flaw manifests when the server processes HTTP requests for directories lacking index.html files. During this process, the server allocates memory to handle the request but fails to properly release this memory resource upon completion of the request handling cycle. This memory leak occurs repeatedly with each subsequent request to directories without index files, leading to progressive memory consumption that can eventually exhaust available system resources. The vulnerability operates at the application layer and demonstrates poor resource management practices in the HTTP server implementation, specifically related to memory allocation and deallocation routines.
From an operational impact perspective, this vulnerability creates a straightforward yet effective denial of service condition that requires minimal sophistication to exploit. Attackers need only repeatedly request URLs pointing to directories without index files to gradually consume system memory until the server becomes unresponsive or crashes entirely. The impact is particularly severe because the vulnerability can be exploited with simple HTTP requests, making it accessible to attackers with basic networking knowledge. This type of vulnerability directly violates the principle of resource isolation and can affect not only the targeted server but potentially impact other services running on the same system due to resource exhaustion.
The vulnerability can be categorized under CWE-400, which addresses "Uncontrolled Resource Consumption," and aligns with ATT&CK technique T1499.1, "Network Denial of Service," highlighting the operational security implications. Organizations running affected versions of Small HTTP Server face significant risk of service disruption, potentially leading to business continuity issues and requiring immediate remediation. The vulnerability also demonstrates the importance of proper memory management in server applications and the need for thorough testing of resource handling under various conditions. Mitigation strategies should include immediate patching to versions that address the memory leak, implementing request rate limiting, and monitoring memory consumption patterns to detect anomalous behavior.
This vulnerability serves as a reminder of the critical importance of proper resource management in server applications and the potential for simple memory leaks to create significant security impacts. The issue underscores the need for comprehensive testing procedures that include stress testing and resource monitoring to identify similar vulnerabilities in other server implementations. Organizations should consider implementing automated monitoring solutions that can detect memory consumption anomalies and trigger alerts when resource usage exceeds normal thresholds, providing early warning of potential exploitation attempts.