CVE-2003-0276 in Pi3Web
Summary
by MITRE
Buffer overflow in Pi3Web 2.0.1 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a GET request with a large number of / characters.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/21/2025
The vulnerability identified as CVE-2003-0276 represents a critical buffer overflow flaw within Pi3Web version 2.0.1, a lightweight web server software that was widely deployed in embedded systems and small-scale network environments during the early 2000s. This particular implementation suffered from inadequate input validation mechanisms that failed to properly handle excessive URL path components, creating a scenario where malicious actors could exploit the software's memory management vulnerabilities through carefully crafted web requests. The flaw specifically manifests when the web server processes GET requests containing an excessive number of forward slash characters, which are interpreted as path separators and subsequently processed without proper bounds checking.
The technical nature of this vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows attackers to write beyond allocated memory boundaries. The flaw occurs at the application layer where Pi3Web fails to validate the length and structure of incoming URL paths, particularly when multiple consecutive forward slashes are present in the request. When processing these malformed requests, the software's internal buffer allocation mechanism becomes overwhelmed, causing memory corruption that can result in either application crashes or potentially arbitrary code execution. The vulnerability's remote exploitability means that attackers need only send specially crafted HTTP GET requests to the affected server without requiring any local access or authentication credentials.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as the potential for arbitrary code execution creates significant security implications for systems running vulnerable versions of Pi3Web. Organizations deploying this software in production environments faced the risk of complete system compromise, especially when the web server was accessible from untrusted networks or when it served content that could be manipulated by attackers. The vulnerability particularly affected embedded systems, IoT devices, and small business network appliances that relied on lightweight web servers for administrative interfaces or basic web services. Attackers could leverage this flaw to gain unauthorized access to system resources, potentially escalating privileges and establishing persistent access points within network infrastructures.
Mitigation strategies for CVE-2003-0276 required immediate software updates and patches from the vendor, as well as network-level defensive measures to protect against exploitation attempts. Organizations should have implemented input validation controls at network boundaries, such as web application firewalls or intrusion detection systems, to filter out malformed HTTP requests containing excessive path components. The vulnerability's classification under the attack pattern taxonomy indicates that it represents a common exploitation technique where attackers target memory corruption flaws through crafted input data, making it a prime example of techniques described in the MITRE ATT&CK framework under the 'Exploitation for Privilege Escalation' and 'Command and Control' categories. System administrators should have also conducted thorough inventory assessments to identify all instances of vulnerable Pi3Web installations and ensured that proper network segmentation was in place to limit the potential blast radius of successful attacks.