CVE-2000-1049 in JRun
Summary
by MITRE
Allaire JRun 3.0 http servlet server allows remote attackers to cause a denial of service via a URL that contains a long string of "." characters.
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Analysis
by VulDB Data Team • 10/11/2025
The vulnerability identified as CVE-2000-1049 affects Allaire JRun 3.0, a web application server that was widely used in the early 2000s for hosting java based web applications. This particular flaw represents a classic denial of service vulnerability that exploits the server's handling of malformed URL requests containing excessive dot characters. The vulnerability resides within the http servlet server component of JRun 3.0, which processes incoming web requests and routes them to appropriate application handlers. When a malicious user submits a URL containing an excessive number of period characters, the server's request parsing mechanism becomes overwhelmed, leading to resource exhaustion and subsequent service disruption. This type of vulnerability falls under the category of improper input validation as defined by CWE-20, where the system fails to properly validate or sanitize input data before processing it. The attack vector is particularly insidious because it requires no authentication or specialized privileges, making it accessible to any remote attacker who can send HTTP requests to the affected server. The vulnerability demonstrates how simple malformed input can lead to significant operational impacts, as the server's response handling becomes completely disrupted by the excessive dot character sequence.
The technical implementation of this vulnerability stems from the server's inadequate handling of URL parsing logic within its servlet container. When processing a URL with an excessive number of consecutive period characters, the JRun 3.0 server attempts to resolve the path by repeatedly processing each dot character in the sequence, leading to exponential processing time and resource consumption. This behavior creates a condition where the server's thread pool becomes saturated with requests that consume disproportionate amounts of CPU and memory resources. The vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and specifically targets the availability aspect of the CIA triad. The server's inability to properly handle the malformed URL results in a complete service disruption, preventing legitimate users from accessing the web application hosted on the server. The attack effectively consumes system resources without providing any legitimate service value, making it a straightforward yet effective method for causing denial of service conditions. This flaw represents a fundamental flaw in the server's request processing pipeline where input validation and resource limiting mechanisms were insufficient to prevent malicious input from causing system-wide disruption.
The operational impact of CVE-2000-1049 extends beyond simple service interruption to potentially affect business operations and user experience. Organizations running Allaire JRun 3.0 servers would experience complete unavailability of their web applications during the attack, leading to potential revenue loss and customer dissatisfaction. The vulnerability's exploitability makes it particularly dangerous as it can be triggered automatically through simple HTTP requests, allowing attackers to maintain persistent denial of service conditions without requiring continuous manual intervention. System administrators would face challenges in identifying and mitigating the attack since it appears as normal HTTP traffic but consumes resources in an abnormal manner. The vulnerability also highlights the importance of proper resource management and input validation in web server implementations, as the attack exploits a fundamental flaw in how the server processes request data. Organizations affected by this vulnerability would need to implement immediate mitigations such as request rate limiting, input length restrictions, and potentially upgrading to newer versions of the JRun platform that address this specific flaw. The vulnerability serves as a reminder of the critical need for robust input validation and resource limiting mechanisms in web application servers to prevent simple attacks from causing significant operational disruptions. From a security perspective, this vulnerability demonstrates how insufficient defensive measures in application servers can lead to complete service outages, emphasizing the need for comprehensive security testing and validation of server implementations. The impact would be particularly severe for organizations relying on JRun 3.0 for critical web applications, as the attack could effectively shut down business operations until the vulnerability is patched or mitigated through alternative means.