CVE-2002-0081 in PHP
Summary
by MITRE
Buffer overflows in (1) php_mime_split in PHP 4.1.0, 4.1.1, and 4.0.6 and earlier, and (2) php3_mime_split in PHP 3.0.x allows remote attackers to execute arbitrary code via a multipart/form-data HTTP POST request when file_uploads is enabled.
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Analysis
by VulDB Data Team • 09/23/2025
The vulnerability identified as CVE-2002-0081 represents a critical buffer overflow flaw affecting PHP versions 4.1.0 through 4.1.1 and 4.0.6 and earlier, specifically within the mime splitting functions php_mime_split and php3_mime_split. This vulnerability arises from insufficient input validation in the handling of multipart/form-data HTTP POST requests, which are commonly used for file uploads and form submissions containing binary data. The flaw manifests when the file_uploads directive is enabled in the PHP configuration, creating an exploitable condition that allows remote attackers to manipulate memory structures through crafted HTTP requests.
The technical exploitation of this vulnerability occurs through the manipulation of boundary delimiters in multipart/form-data requests, where the php_mime_split functions fail to properly validate the length of boundary strings before processing them. This inadequate boundary validation leads to a classic buffer overflow condition where attacker-controlled data exceeds the allocated buffer space, potentially overwriting adjacent memory locations including return addresses and function pointers. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which directly enables arbitrary code execution capabilities for remote attackers.
Operationally, this vulnerability poses significant risks to web applications running vulnerable PHP versions, particularly those that accept file uploads or process form data with file attachments. Attackers can craft malicious HTTP POST requests containing oversized boundary strings that trigger the buffer overflow during mime parsing, potentially leading to complete system compromise. The attack vector is particularly dangerous because it requires no authentication and can be executed through standard web browser interactions, making it highly exploitable in real-world scenarios. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1190 for exploitation of remote services and T1059 for command execution.
The impact of this vulnerability extends beyond simple code execution to include potential privilege escalation and persistent system compromise, as successful exploitation can allow attackers to gain unauthorized access to web server processes and potentially the underlying operating system. Organizations running affected PHP versions face critical exposure, particularly in environments where file upload functionality is enabled and user input is not properly sanitized. The vulnerability demonstrates the importance of proper input validation and memory management practices in web application development, emphasizing the need for regular security updates and thorough code review processes.
Mitigation strategies for CVE-2002-0081 require immediate patching of affected PHP installations to versions that contain proper boundary length validation and buffer overflow protection mechanisms. System administrators should disable file_uploads functionality when not required, implement proper input validation at the application level, and consider deploying web application firewalls to detect and block malicious multipart/form-data requests. Additionally, regular security audits and vulnerability assessments should be conducted to identify and remediate similar buffer overflow conditions in other application components. The vulnerability underscores the necessity of maintaining up-to-date software versions and implementing comprehensive security controls to prevent exploitation of memory corruption vulnerabilities in web applications.