CVE-2006-6123 in Photo Gallery
Summary
by MITRE
Coppermine Photo Gallery (CPG) 1.4.8 stable, with register_globals enabled, allows remote attackers to bypass XSS protection and set arbitrary variables via a query string that causes the variable to be defined in global space, with separate _GET, _REQUEST, or other critical parameters, which are unset by the protection scheme and prevent the original variable from being detected.
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Analysis
by VulDB Data Team • 04/29/2026
The vulnerability described in CVE-2006-6123 affects Coppermine Photo Gallery version 1.4.8 when running with register_globals enabled, creating a critical security flaw that undermines the application's cross-site scripting protection mechanisms. This issue stems from the improper handling of HTTP request parameters within the PHP configuration that allows malicious actors to manipulate global variable scope and bypass security controls designed to prevent XSS attacks.
The technical flaw occurs when the application processes query strings containing parameters that collide with internal variables used for security protection. When register_globals is enabled, PHP automatically creates global variables from HTTP request data, including GET, POST, and COOKIE parameters. The Coppermine application implements a protection scheme that attempts to unset certain critical parameters like _GET, _REQUEST, and others to prevent XSS vulnerabilities, but this protection mechanism fails when attackers craft malicious query strings that define variables in the global namespace before the cleanup process occurs.
This vulnerability operates through a specific exploitation pattern where attackers construct query strings that define variables in global scope, effectively overriding the protection mechanisms designed to detect and neutralize potentially malicious input. The flaw enables remote attackers to bypass XSS safeguards by manipulating the order and content of parameters in the query string, allowing them to inject malicious code that would otherwise be filtered or sanitized by the application's security measures. The protection scheme's failure to properly handle variable scoping when register_globals is enabled creates a pathway for attackers to inject arbitrary variables that can be used to manipulate application behavior.
The operational impact of this vulnerability is significant as it allows attackers to bypass multiple layers of security protection that should prevent cross-site scripting attacks. By exploiting this flaw, attackers can execute malicious scripts in the context of the victim's browser, potentially leading to session hijacking, data theft, or further exploitation of the vulnerable system. The vulnerability affects not just the basic XSS protection but also undermines the application's overall security posture by allowing attackers to manipulate internal application variables that control access and data handling.
This vulnerability aligns with CWE-79, Cross-Site Scripting, and specifically relates to CWE-1077, which deals with improper handling of variables in global scope when register_globals is enabled. The flaw also connects to ATT&CK techniques involving code injection and privilege escalation through web application vulnerabilities. Organizations should implement immediate mitigations including disabling register_globals in PHP configuration, updating to patched versions of Coppermine Photo Gallery, and implementing proper input validation and sanitization. Additionally, the application should be configured to explicitly unset or sanitize all potentially dangerous parameters before they can be processed, regardless of the PHP register_globals setting. The vulnerability demonstrates the critical importance of proper variable scope management in web applications and the risks associated with legacy PHP configurations that enable potentially dangerous features like register_globals.