CVE-2010-0397 in PHP
Summary
by MITRE
The xmlrpc extension in PHP 5.3.1 does not properly handle a missing methodName element in the first argument to the xmlrpc_decode_request function, which allows context-dependent attackers to cause a denial of service (NULL pointer dereference and application crash) and possibly have unspecified other impact via a crafted argument.
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Analysis
by VulDB Data Team • 05/02/2026
The vulnerability identified as CVE-2010-0397 resides within the xmlrpc extension of PHP version 5.3.1, representing a critical security flaw that demonstrates poor input validation and error handling practices. This issue specifically affects the xmlrpc_decode_request function which is designed to parse XML-RPC requests and convert them into PHP data structures. The vulnerability manifests when the function encounters a malformed XML-RPC request where the methodName element is absent from the first argument, creating a scenario where the application fails to properly validate incoming data before attempting to process it. Such a flaw represents a classic example of insufficient input sanitization that can be exploited by malicious actors to disrupt service availability.
The technical exploitation of this vulnerability occurs through a NULL pointer dereference condition that arises when the xmlrpc_decode_request function attempts to access a method name that does not exist within the parsed XML structure. When the methodName element is missing, the function fails to properly handle this edge case and instead attempts to dereference a NULL pointer, leading to an application crash. This behavior aligns with CWE-476, which describes NULL pointer dereference vulnerabilities, and demonstrates how improper error handling can result in complete application termination. The flaw essentially creates a situation where legitimate XML-RPC requests can be crafted to trigger memory access violations, causing the PHP process to terminate abruptly and leaving the web server unable to process subsequent requests.
From an operational perspective, this vulnerability presents a significant risk to web applications that rely on XML-RPC functionality for communication with external services or client applications. The denial of service impact means that attackers can systematically disrupt services by sending malformed requests that cause application crashes, effectively rendering the affected web server or application unavailable to legitimate users. This vulnerability is particularly dangerous in high-traffic environments where such attacks could be amplified through automated tools to cause sustained service disruption. The unspecified other impacts mentioned in the description suggest that beyond simple denial of service, there may be potential for additional security implications including information disclosure or privilege escalation depending on the specific implementation and system configuration.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to PHP versions that contain the patched xmlrpc extension, typically PHP 5.3.2 or later. The fix implemented by the PHP development team involved adding proper validation checks to ensure that the methodName element exists before attempting to process it, thereby preventing the NULL pointer dereference condition. Additionally, administrators should consider implementing input validation at the web server level using mod_security rules or similar filtering mechanisms to detect and block malformed XML-RPC requests before they reach the PHP application layer. This vulnerability also highlights the importance of following security best practices such as the principle of least privilege and input validation as outlined in the OWASP Top Ten security risks, where proper error handling and input sanitization are fundamental requirements for preventing both denial of service and potential exploitation for more severe security incidents. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and denial of service techniques, emphasizing the need for comprehensive application security testing and regular vulnerability assessments to identify similar flaws in other system components.