CVE-2002-0142 in Pi3Web
Summary
by MITRE
CGI handler in John Roy Pi3Web for Windows 2.0 beta 1 and 2 allows remote attackers to cause a denial of service (crash) via a series of requests whose physical path is exactly 260 characters long and ends in a series of . (dot) characters.
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Analysis
by VulDB Data Team • 09/22/2025
The vulnerability identified as CVE-2002-0142 represents a denial of service flaw within the John Roy Pi3Web web server version 2.0 beta 1 and 2 for Windows systems. This vulnerability specifically targets the CGI handler component of the web server, which is responsible for processing dynamic content requests. The flaw manifests when remote attackers exploit a particular path length condition that triggers a system crash, effectively rendering the web server unavailable to legitimate users.
The technical mechanism behind this vulnerability involves a specific buffer handling issue in the CGI processing module. When a malicious request is made with a physical path that is exactly 260 characters long and concludes with multiple dot characters, the web server's internal buffer management fails to properly handle this input. This condition creates a situation where the server's memory management routines encounter an overflow or improper boundary condition that results in an application crash. The precise character count of 260 characters corresponds to the maximum path length limitation inherent in Windows file systems, making this attack vector particularly effective against systems running the affected Pi3Web versions.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited by attackers to systematically degrade web server availability. The attack requires minimal complexity to execute since it only involves crafting a specific URL pattern with the exact character count and ending sequence. This makes it particularly dangerous in environments where web servers are critical infrastructure components, as the vulnerability can be exploited repeatedly to maintain denial of service conditions. The vulnerability also demonstrates poor input validation practices within the web server's core processing components, indicating potential weaknesses in the overall security architecture.
This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and reflects common issues in legacy web server implementations that lacked proper bounds checking for file path inputs. The attack pattern follows techniques described in the MITRE ATT&CK framework under the T1499 category for network denial of service, specifically targeting application-level vulnerabilities to disrupt service availability. Organizations running affected versions of Pi3Web should immediately implement mitigations including input length validation, request rate limiting, and protocol-level restrictions to prevent exploitation. The vulnerability also highlights the importance of proper path handling in web applications and underscores the need for comprehensive testing of boundary conditions in file system interactions.
The remediation approach for this vulnerability requires immediate patching of the Pi3Web server software to version 2.0 beta 3 or later, which contains the necessary fixes for the buffer handling issue. System administrators should also implement network-level controls to monitor and restrict requests that exceed normal path length parameters, as well as deploy intrusion detection systems that can identify patterns consistent with this specific attack vector. Additionally, organizations should conduct comprehensive vulnerability assessments to identify other legacy web server components that might exhibit similar buffer handling weaknesses, particularly in older implementations that may not have received security updates.