CVE-2001-0302 in Pi3Web
Summary
by MITRE
Buffer overflow in tstisapi.dll in Pi3Web 1.0.1 web server allows remote attackers to cause a denial of service, and possibly execute arbitrary commands, via a long URL.
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Analysis
by VulDB Data Team • 10/07/2025
The vulnerability identified as CVE-2001-0302 represents a critical buffer overflow flaw within the tstisapi.dll component of Pi3Web 1.0.1 web server software. This issue resides in the handling of Uniform Resource Locators and demonstrates a classic stack-based buffer overflow condition that can be exploited through malformed input. The vulnerability specifically affects the Internet Information Services (IIS) API integration within the Pi3Web server, where the application fails to properly validate input length when processing URL requests. The buffer overflow occurs when the server receives a URL exceeding the allocated buffer space, causing memory corruption that can lead to unpredictable behavior. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The flaw exists due to inadequate input validation mechanisms within the web server's URL processing pipeline, particularly within the ISAPI extension that handles requests.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution capabilities. When a remote attacker crafts a specially formatted URL containing excessive data, the buffer overflow can overwrite critical memory segments including return addresses and function pointers. This memory corruption can be leveraged to redirect program execution flow, potentially allowing attackers to inject and execute malicious code on the vulnerable system. The vulnerability's exploitability is enhanced by the fact that it requires no authentication, making it particularly dangerous as attackers can exploit it remotely without prior access credentials. The affected Pi3Web 1.0.1 server configuration creates a pathway for attackers to escalate privileges and gain unauthorized control over the web server. According to the ATT&CK framework, this vulnerability maps to technique T1203 - Exploitation for Client Execution, where adversaries leverage application vulnerabilities to execute arbitrary code. The attack surface is particularly concerning given that web servers are typically accessible from external networks, providing attackers with direct access points to exploit this buffer overflow condition.
Mitigation strategies for CVE-2001-0302 should prioritize immediate patching and system hardening measures to prevent exploitation. Organizations must upgrade to newer versions of Pi3Web that address this buffer overflow vulnerability, as the original 1.0.1 release contains no built-in protections against such attacks. Network administrators should implement input validation at multiple layers including web application firewalls and proxy servers to filter out excessively long URLs before they reach the vulnerable web server. The implementation of address space layout randomization and stack canaries can provide additional defense-in-depth measures that make exploitation more difficult. Security monitoring should include detection of unusually long URL patterns and malformed requests that could indicate attempted exploitation. System administrators should also consider implementing intrusion detection systems that can identify patterns consistent with buffer overflow exploitation attempts. The vulnerability demonstrates the importance of proper input validation and bounds checking in web server applications, aligning with security best practices outlined in the OWASP Top Ten and NIST cybersecurity frameworks. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other web server components and applications that may be susceptible to similar buffer overflow conditions.