CVE-2010-3710 in PHP
Summary
by MITRE
Stack consumption vulnerability in the filter_var function in PHP 5.2.x through 5.2.14 and 5.3.x through 5.3.3, when FILTER_VALIDATE_EMAIL mode is used, allows remote attackers to cause a denial of service (memory consumption and application crash) via a long e-mail address string.
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Analysis
by VulDB Data Team • 09/28/2021
The vulnerability identified as CVE-2010-3710 represents a critical stack consumption issue within PHP's filter_var function when processing email addresses in validation mode. This flaw affects PHP versions ranging from 5.2.0 through 5.2.14 and 5.3.0 through 5.3.3, creating a significant security concern for web applications that rely on email validation. The vulnerability stems from insufficient input validation handling within the filter_var function's implementation, specifically when the FILTER_VALIDATE_EMAIL flag is employed to process potentially malicious email address strings.
The technical exploitation of this vulnerability occurs through a carefully crafted long email address string that triggers excessive stack memory consumption during the validation process. When PHP processes such malformed input, the recursive parsing algorithm within the filter_var function becomes susceptible to stack exhaustion, causing the application to consume excessive memory resources and ultimately leading to application crashes. This behavior manifests as a denial of service condition where legitimate users cannot access services due to the application becoming unresponsive or terminating unexpectedly. The vulnerability operates at the core level of PHP's input validation mechanisms, making it particularly dangerous as it can be triggered through any web interface that utilizes email validation functionality.
From an operational impact perspective, this vulnerability creates substantial risk for web applications and hosting environments that depend on PHP for email processing. Attackers can exploit this weakness by submitting extremely long email addresses to any form or API endpoint that validates email inputs, resulting in resource exhaustion and service disruption. The vulnerability aligns with CWE-400, which categorizes "Uncontrolled Resource Consumption" as a fundamental weakness affecting software systems. The attack vector typically involves HTTP requests containing malformed email addresses, making it easily executable through standard web application interfaces without requiring special privileges or complex attack chains.
The implications extend beyond simple denial of service, as this vulnerability can be leveraged to exhaust system resources and potentially cause cascading failures in multi-tenant hosting environments. Organizations running PHP-based applications must consider the broader impact on their infrastructure, including potential resource contention affecting other applications sharing the same hosting environment. Mitigation strategies should include immediate patching to PHP versions that address this specific stack consumption issue, implementing input length restrictions for email validation, and deploying application-level rate limiting to prevent abuse of validation functions. The vulnerability demonstrates the importance of proper stack management and input validation in server-side scripting environments, aligning with ATT&CK technique T1499.004 for Denial of Service through resource exhaustion. Organizations should also implement comprehensive monitoring to detect unusual memory consumption patterns and establish robust input sanitization practices to prevent similar issues in future software versions.