CVE-2007-6039 in PHP
Summary
by MITRE
PHP 5.2.5 and earlier allows context-dependent attackers to cause a denial of service (application crash) via a long string in (1) the domain parameter to the dgettext function, the message parameter to the (2) dcgettext or (3) gettext function, the msgid1 parameter to the (4) dngettext or (5) ngettext function, or (6) the classname parameter to the stream_wrapper_register function. NOTE: this might not be a vulnerability in most web server environments that support multiple threads, unless this issue can be demonstrated for code execution.
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Analysis
by VulDB Data Team • 04/10/2025
The vulnerability described in CVE-2007-6039 represents a classic buffer overflow condition affecting PHP applications that process internationalization functions. This issue stems from insufficient input validation within several core internationalization functions including dgettext, dcgettext, gettext, dngettext, and ngettext, as well as the stream_wrapper_register function. The flaw occurs when these functions receive excessively long string inputs in their respective parameters, leading to memory corruption that can result in application crashes or denial of service conditions. The vulnerability is particularly concerning because it affects fundamental localization capabilities that are widely used across web applications, making it a potential vector for widespread disruption.
The technical implementation of this vulnerability involves the improper handling of string parameters within PHP's internationalization subsystem. When a maliciously long string is passed to any of the affected functions, the underlying memory allocation and string processing routines fail to properly validate the input length, causing buffer overflows that can corrupt adjacent memory regions. This memory corruption typically manifests as application crashes or segmentation faults, effectively rendering the targeted PHP application unavailable to legitimate users. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, where the excessive string length exceeds the allocated buffer space during string processing operations.
From an operational perspective, this vulnerability presents significant risks to web application availability and system stability. The denial of service impact can be particularly damaging in production environments where PHP applications handle high volumes of user requests. Attackers can exploit this weakness by crafting malicious requests containing overly long parameter values, causing the target application to crash repeatedly and potentially consuming system resources. The vulnerability's impact extends beyond simple service disruption, as it can be leveraged in distributed denial of service attacks or used to create persistent availability issues. According to ATT&CK framework category T1499, this represents a resource exhaustion technique that can be used to compromise system availability and service integrity.
The exploitation of this vulnerability requires minimal technical sophistication and can be performed through standard web application request manipulation techniques. Attackers need only craft HTTP requests with excessively long parameter values to trigger the buffer overflow conditions in the affected PHP functions. In multi-threaded web server environments, the vulnerability's impact may be somewhat mitigated, though it still represents a significant risk for code execution exploitation. The limited scope of the vulnerability means that it primarily affects applications that utilize internationalization functions, but given the widespread adoption of these functions in modern web applications, the potential attack surface remains substantial. Organizations should prioritize patching this vulnerability as it represents a straightforward denial of service vector that can be exploited without requiring advanced technical skills or specialized tools.