CVE-2002-0899 in Falcon Web Server
Summary
by MITRE
Falcon web server 2.0.0.1021 and earlier allows remote attackers to bypass access restrictions for protected files via a URL whose directory portion ends in a . (dot).
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Analysis
by VulDB Data Team • 09/11/2025
The vulnerability described in CVE-2002-0899 represents a critical access control flaw in the Falcon web server version 2.0.0.1021 and earlier releases. This issue stems from improper handling of URL path traversal sequences where directory components ending with a dot character can be exploited to bypass authentication and authorization mechanisms. The flaw exists at the core of the web server's file access validation logic, allowing malicious actors to craft specific URL requests that circumvent protected resource restrictions.
The technical implementation of this vulnerability leverages the way the Falcon web server processes directory paths in URLs. When a request contains a directory component that terminates with a period character, the server's internal path resolution algorithm fails to properly validate the request against configured access controls. This occurs because the dot character at the end of directory names is often interpreted as a special path reference in Unix-like systems, but the Falcon server does not adequately sanitize or normalize these path components before performing access checks. The vulnerability specifically targets the server's directory traversal handling rather than the file system itself, making it particularly insidious as it exploits the application logic rather than underlying OS-level protections.
From an operational perspective, this vulnerability poses significant risks to web applications hosted on affected Falcon servers. Attackers can exploit this flaw to gain unauthorized access to protected resources such as configuration files, administrative interfaces, user data, or sensitive application components. The impact extends beyond simple information disclosure as it can enable further attacks including privilege escalation, data manipulation, or complete system compromise depending on the nature of the protected resources. The vulnerability's remote exploitability means that attackers do not require physical access or local system credentials to leverage the flaw, making it particularly dangerous in internet-facing environments.
The security implications of this vulnerability align with CWE-22, which describes improper limitation of a pathname to a restricted directory, and can be mapped to ATT&CK technique T1078 for valid accounts and T1566 for social engineering. Organizations running affected Falcon web server versions should implement immediate mitigations including updating to patched versions, implementing URL path validation rules, and configuring additional access control layers. The recommended approach involves deploying web application firewalls that can detect and block suspicious path traversal patterns, enforcing strict input validation on all URL components, and conducting thorough security reviews of all web server configurations. Additionally, system administrators should consider implementing monitoring solutions that can detect unusual access patterns or attempts to exploit path traversal vulnerabilities in real-time.