CVE-2006-5525 in PHP-Nuke
Summary
by MITRE
Incomplete blacklist vulnerability in mainfile.php in PHP-Nuke 7.9 and earlier allows remote attackers to conduct SQL injection attacks via (1) "/**/UNION " or (2) " UNION/**/" sequences, which are not rejected by the protection mechanism, as demonstrated by a SQL injection via the eid parameter in a search action in the Encyclopedia module in modules.php.
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Analysis
by VulDB Data Team • 04/25/2026
The vulnerability identified as CVE-2006-5525 represents a critical SQL injection flaw in PHP-Nuke version 7.9 and earlier installations. This security weakness stems from an incomplete blacklist implementation within the mainfile.php component that fails to properly filter or reject malicious SQL injection attempts. The vulnerability specifically affects the Encyclopedia module's search functionality where the eid parameter is processed without adequate input sanitization. Attackers can exploit this flaw by crafting SQL injection payloads that utilize comment sequences such as "/*/UNION " or " UNION/*/" which bypass the existing protection mechanisms due to the incomplete blacklist approach.
The technical nature of this vulnerability aligns with CWE-94, which describes improper control of generation of code, and more specifically relates to CWE-89, SQL injection, where the system fails to properly escape or validate user-supplied input before incorporating it into SQL queries. The flaw demonstrates a classic inadequate input validation pattern where the system attempts to block known malicious patterns but fails to account for obfuscation techniques that can circumvent basic filtering. The protection mechanism in mainfile.php relies on a static blacklist of SQL keywords and patterns, but the use of comment characters /**/ effectively masks the UNION keyword, allowing the malicious payload to pass undetected through the filtering layer.
From an operational perspective, this vulnerability poses significant risks to systems running affected PHP-Nuke versions as it enables remote attackers to execute arbitrary SQL commands against the underlying database. The exploitation occurs through the Encyclopedia module's search functionality, where the eid parameter is directly incorporated into SQL queries without proper sanitization. Successful exploitation could allow attackers to extract sensitive data, modify database contents, or potentially escalate privileges within the database environment. The vulnerability's impact extends beyond simple data theft as it could lead to complete system compromise if database credentials are accessible or if the attacker can leverage the SQL injection to gain further access to the underlying server infrastructure.
The attack vector for CVE-2006-5525 demonstrates techniques that map to ATT&CK tactics including T1071.004 Application Layer Protocol: DNS and T1213.002 Data from Information Repositories, where attackers can manipulate application behavior to extract data from database systems. The use of comment obfuscation techniques in the payload represents a common evasion method that bypasses basic security controls, highlighting the limitations of simple pattern matching approaches to input validation. Organizations running affected systems should immediately implement mitigations including input validation improvements, proper parameterized queries, and comprehensive security testing to address this vulnerability.
The remediation approach for this vulnerability requires immediate patching of PHP-Nuke installations to versions that address the incomplete blacklist issue. Security teams should implement additional layers of protection including proper parameterized queries, robust input validation mechanisms, and comprehensive testing of all user-supplied inputs. The vulnerability underscores the importance of using positive security models over negative blacklists and implementing proper database access controls to limit the impact of potential SQL injection attacks. Organizations should also consider implementing web application firewalls and database activity monitoring to detect and prevent exploitation attempts of similar vulnerabilities in their systems.