CVE-2001-0925 in HTTP Server
Summary
by MITRE
The default installation of Apache before 1.3.19 allows remote attackers to list directories instead of the multiview index.html file via an HTTP request for a path that contains many / (slash) characters, which causes the path to be mishandled by (1) mod_negotiation, (2) mod_dir, or (3) mod_autoindex.
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Analysis
by VulDB Data Team • 10/01/2025
This vulnerability exists in Apache HTTP Server versions prior to 1.3.19 where the default installation configuration contains a path traversal flaw that can be exploited by remote attackers to enumerate directory contents. The issue specifically manifests when an attacker crafts an HTTP request with an excessive number of forward slash characters in the requested path, causing the web server to mishandle the path resolution process through three critical modules: mod_negotiation, mod_dir, and mod_autoindex. The vulnerability stems from the server's inability to properly sanitize or normalize path components when processing requests with deeply nested or excessively slashed paths, leading to unexpected behavior in the directory listing mechanism.
The technical exploitation occurs because Apache's internal path handling logic fails to properly canonicalize or validate the requested path before processing it through the module chain. When a path containing numerous consecutive slash characters is submitted, the server's path resolution algorithms in mod_negotiation, which handles content negotiation, mod_dir, which manages directory indexing, and mod_autoindex, which generates automatic directory listings, all process the malformed path differently. This inconsistency in path handling causes the server to return directory listings instead of the expected index.html file or other configured default documents, effectively bypassing normal access controls and exposing directory structures to unauthorized users.
The operational impact of this vulnerability is significant as it provides attackers with unauthorized directory enumeration capabilities that can reveal sensitive information about the server's file structure, potentially exposing configuration files, source code, or other confidential data. Attackers can leverage this information to plan further exploitation attempts, identify vulnerable applications, or discover additional attack vectors within the web server environment. The vulnerability affects the fundamental security principle of least privilege by allowing unauthorized access to directory listings that should normally be protected or hidden from public view. This issue directly relates to CWE-22, which addresses path traversal vulnerabilities, and can be categorized under ATT&CK technique T1083 for discovering files and directories, making it a critical concern for organizations relying on Apache web servers.
The recommended mitigation strategy involves upgrading to Apache HTTP Server version 1.3.19 or later, which contains the necessary patches to properly handle malformed paths and prevent the path traversal behavior. Organizations should also implement proper input validation and sanitization at the web server level, configure appropriate access controls, and monitor for unusual directory listing requests. Additionally, security measures such as disabling directory browsing, implementing proper authentication mechanisms, and regularly updating server software can help prevent exploitation of this vulnerability. Network administrators should also consider implementing intrusion detection systems that can identify and alert on suspicious path traversal patterns, particularly those involving excessive slash characters in HTTP requests.