CVE-2002-0717 in PHP
Summary
by MITRE
PHP 4.2.0 and 4.2.1 allows remote attackers to cause a denial of service and possibly execute arbitrary code via an HTTP POST request with certain arguments in a multipart/form-data form, which generates an error condition that is not properly handled and causes improper memory to be freed.
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Analysis
by VulDB Data Team • 09/14/2025
The vulnerability identified as CVE-2002-0717 represents a critical security flaw in PHP versions 4.2.0 and 4.2.1 that enables remote attackers to exploit a memory handling error through specially crafted HTTP POST requests. This vulnerability operates within the context of web application security where PHP serves as the primary server-side scripting language for dynamic web content generation. The flaw specifically manifests when the web server processes multipart/form-data encoded HTTP POST requests, which are commonly used for file uploads and complex form submissions. The vulnerability falls under the category of improper error handling and memory management issues that can lead to system instability and potential code execution.
The technical mechanism behind this vulnerability involves the improper handling of error conditions that occur during the processing of malformed multipart/form-data requests. When PHP encounters certain arguments within these requests, it generates an error condition that is not properly managed by the application's error handling routines. This failure in error management leads to situations where memory that should not be freed is prematurely deallocated, creating a scenario where the application's memory management system becomes corrupted. The improper memory freeing process can result in memory corruption that may be exploited by attackers to execute arbitrary code on the vulnerable system. This type of vulnerability is classified as a memory corruption vulnerability and aligns with CWE-122 which addresses heap-based buffer overflow conditions, though it specifically involves improper memory deallocation rather than buffer overflows.
The operational impact of CVE-2002-0717 extends beyond simple denial of service to potentially allow full system compromise. Attackers can leverage this vulnerability to cause the web server to crash repeatedly, resulting in denial of service that affects legitimate users and business operations. More critically, the memory corruption aspects of this vulnerability provide opportunities for code execution, allowing attackers to run malicious code with the privileges of the web server process. This can lead to complete system compromise, data theft, or further lateral movement within the network infrastructure. The vulnerability is particularly dangerous because it requires minimal privileges to exploit and can be triggered through standard web browsing activities, making it an attractive target for automated attacks. The attack pattern aligns with techniques described in the MITRE ATT&CK framework under the T1059.007 sub-technique for command and scripting interpreter, as attackers can potentially execute arbitrary code on the target system.
Mitigation strategies for this vulnerability require immediate patching of affected PHP installations to versions that properly handle error conditions in multipart/form-data processing. System administrators should implement network-based protections such as web application firewalls that can detect and block suspicious POST requests containing malformed multipart data. Additionally, implementing input validation controls at the application level can help prevent malicious requests from reaching the vulnerable PHP processing layer. Organizations should also consider implementing monitoring and alerting mechanisms to detect unusual denial of service patterns or unexpected process crashes that might indicate exploitation attempts. The vulnerability highlights the importance of proper error handling and memory management in server-side applications, emphasizing that even seemingly minor issues in error conditions can lead to significant security consequences. Security teams should also conduct regular vulnerability assessments to identify other potential memory corruption issues within their PHP applications and web server configurations.