CVE-2001-0175 in Fasttrack Server
Summary
by MITRE
The caching module in Netscape Fasttrack Server 4.1 allows remote attackers to cause a denial of service (resource exhaustion) by requesting a large number of non-existent URLs.
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Analysis
by VulDB Data Team • 10/08/2025
The vulnerability described in CVE-2001-0175 represents a classic resource exhaustion attack targeting the caching module of Netscape FastTrack Server version 4.1. This flaw enables remote attackers to systematically consume server resources through repeated requests for non-existent URLs, ultimately leading to service disruption. The issue stems from inadequate resource management within the server's caching mechanism, which fails to properly handle or limit requests for invalid resources. The vulnerability specifically affects the server's ability to maintain proper resource allocation when processing multiple concurrent requests for nonexistent web paths, creating a condition where legitimate requests cannot be processed due to resource depletion.
The technical implementation of this vulnerability operates through a straightforward but effective mechanism where attackers send numerous HTTP requests targeting URLs that do not exist within the server's content structure. The caching module in Netscape FastTrack Server 4.1 appears to store or attempt to cache these non-existent URLs without proper bounds checking or rate limiting mechanisms. As the server processes each request for a non-existent resource, it allocates memory and processing resources to handle the lookup and response generation, even though no actual content exists for these paths. This behavior creates a resource leak scenario where each request consumes server capacity, and the cumulative effect of multiple simultaneous requests leads to complete resource exhaustion. The vulnerability is particularly concerning because it requires minimal technical expertise to exploit, making it accessible to attackers with basic networking knowledge.
The operational impact of CVE-2001-0175 extends beyond simple service disruption to potentially compromise the entire server availability and performance. When the caching module becomes overwhelmed with requests for non-existent resources, legitimate users experience complete denial of service, as the server cannot process any new requests or maintain existing connections. This vulnerability affects not only the specific web server instance but also impacts any applications or services dependent on the server's availability. The resource exhaustion can lead to system instability, requiring manual intervention to restore normal operations through server restarts or manual resource cleanup. Network administrators may observe significant performance degradation, increased memory consumption, and potential system crashes as the server's resources become completely consumed by the malicious request patterns.
Mitigation strategies for this vulnerability require both immediate defensive measures and long-term architectural improvements to prevent resource exhaustion attacks. Organizations should implement rate limiting mechanisms at the network level to restrict the number of requests per client within a given time period, effectively preventing the exploitation pattern from overwhelming server resources. Network administrators should configure the Netscape FastTrack Server to implement proper timeout values and connection limits to prevent indefinite resource allocation for invalid requests. The implementation of intrusion detection systems can help identify and block suspicious request patterns that match the exploitation criteria of this vulnerability. Additionally, the affected server should be updated to a patched version of Netscape FastTrack Server or migrated to a more modern web server solution that properly implements resource management and request handling. From a cybersecurity perspective, this vulnerability aligns with CWE-400, which addresses "Uncontrolled Resource Consumption" and represents a common pattern in web server security that has been addressed through various defensive measures including the implementation of proper input validation, resource limiting, and rate limiting controls. The attack pattern also corresponds to techniques described in the ATT&CK framework under defensive evasion and resource exhaustion tactics, emphasizing the need for proper server hardening and monitoring to detect and prevent such attacks.