CVE-2000-1050 in JRun
Summary
by MITRE
Allaire JRun 3.0 http servlet server allows remote attackers to directly access the WEB-INF directory via a URL request that contains an extra "/" in the beginning of the request (aka the "extra leading slash").
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Analysis
by VulDB Data Team • 10/11/2025
The vulnerability described in CVE-2000-1050 represents a critical directory traversal flaw within the Allaire JRun 3.0 web application server implementation. This security weakness specifically affects the http servlet server component and enables remote attackers to bypass normal access controls by manipulating URL request paths. The vulnerability exploits a fundamental flaw in how the server processes incoming requests that contain an extra leading forward slash character at the beginning of the URL path. This seemingly minor deviation from standard URL formatting creates a significant security gap that allows unauthorized access to sensitive server directories.
The technical exploitation of this vulnerability occurs through the manipulation of URL request syntax where attackers append an additional forward slash at the beginning of their request path. When the JRun 3.0 server processes such requests, it fails to properly validate or normalize the URL path, allowing the extra slash to alter the intended directory resolution process. This flaw falls under the category of improper input validation as defined by CWE-20, where the system fails to properly sanitize or normalize user-provided input before processing. The vulnerability specifically targets the web server's path resolution mechanism, which should normally enforce proper access controls and directory boundaries.
The operational impact of this vulnerability is severe as it grants attackers direct access to the WEB-INF directory, which typically contains critical application configuration files, deployment descriptors, and other sensitive server components. The WEB-INF directory in Java web applications is designed to be protected from direct HTTP access and contains essential files such as web.xml configuration, application classes, and potentially database connection information. By bypassing normal access controls, attackers can extract sensitive configuration data, potentially leading to further exploitation opportunities including credential theft, application compromise, and system reconnaissance.
This vulnerability aligns with several ATT&CK framework techniques including T1071.004 Application Layer Protocol: Web Protocols and T1566.001 Phishing: Spearphishing Attachment. The flaw enables attackers to perform reconnaissance and information gathering through web protocol manipulation, while the exposed WEB-INF directory content could contain information useful for subsequent attack phases. The vulnerability also demonstrates characteristics of T1083 File and Directory Discovery, as attackers can systematically explore server directories through manipulated URL requests. Organizations running Allaire JRun 3.0 servers were particularly vulnerable to this type of attack due to the server's failure to implement proper path normalization and validation mechanisms.
The recommended mitigations for this vulnerability include immediate patching of the Allaire JRun 3.0 server to the latest available security updates from the vendor, as well as implementing proper URL path validation and normalization at the server level. Network-level protections such as web application firewalls and URL filtering rules can provide additional defense-in-depth measures. Organizations should also conduct thorough security assessments of their web application server configurations to identify and remediate similar path traversal vulnerabilities in other components. The vulnerability underscores the importance of proper input validation and access control implementation in web server software, particularly in the context of Java-based application servers where directory traversal attacks remain a persistent threat vector.