CVE-2001-0391 in Xitami
Summary
by MITRE
Xitami 2.5d4 and earlier allows remote attackers to crash the server via an HTTP request to the /aux directory.
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Analysis
by VulDB Data Team • 10/06/2025
The vulnerability identified as CVE-2001-0391 represents a critical denial of service flaw affecting Xitami web server versions 2.5d4 and earlier. This vulnerability resides in the server's handling of specific HTTP requests directed toward the auxiliary directory structure, which is a fundamental component of the Windows operating system used for device drivers and system services. The affected Xitami versions fail to properly validate or sanitize incoming requests targeting the /aux directory path, creating a condition where malicious actors can exploit this weakness to cause the web server to crash or become unresponsive.
The technical exploitation of this vulnerability leverages the inherent Windows filesystem behavior where certain reserved directory names including aux, con, prn, and others have special significance and cannot be directly accessed through standard file operations. When Xitami receives an HTTP request attempting to access resources within the /aux directory, the server's request processing mechanism does not adequately filter or reject these malformed requests, leading to a buffer overflow or resource exhaustion condition that ultimately results in server termination. This flaw operates at the application layer of the network stack and requires no authentication or elevated privileges to exploit, making it particularly dangerous in environments where public web servers are accessible to unauthenticated users.
The operational impact of this vulnerability extends beyond simple server downtime, as it can be weaponized to disrupt critical web services and potentially enable more sophisticated attack vectors. Network administrators and security professionals must understand that this vulnerability can be exploited automatically through simple HTTP request manipulation, making it an attractive target for automated scanning tools and malicious actors seeking to cause disruption. The crash condition typically manifests as immediate service termination or indefinite hanging of server processes, effectively rendering the web server unavailable to legitimate users and potentially exposing the underlying system to further exploitation attempts.
Organizations running affected Xitami versions should immediately implement mitigations including upgrading to patched versions of the software or applying vendor-specific security patches that address the improper request handling. The vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of inadequate input validation in web server applications. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique for network denial of service, and could potentially serve as a precursor to more advanced attacks if the server environment contains additional vulnerabilities. System administrators should also consider implementing network-level restrictions to prevent access to reserved directory paths and deploy intrusion detection systems to monitor for suspicious HTTP request patterns targeting these known vulnerable paths.