CVE-2006-2059 in IP.Board
Summary
by MITRE
action_public/search.php in Invision Power Board (IPB) 2.1.x and 2.0.x before 20060425 allows remote attackers to execute arbitrary PHP code via a search with a crafted value of the lastdate parameter, which alters the behavior of a regular expression to add a "#e" (execute) modifier.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 12/10/2025
This vulnerability exists in Invision Power Board versions 2.1.x and 2.0.x prior to the 20060425 release, specifically within the action_public/search.php script. The flaw represents a classic regular expression injection vulnerability that allows remote attackers to execute arbitrary PHP code through crafted input manipulation. The vulnerability occurs when the lastdate parameter is processed without proper sanitization, enabling attackers to inject malicious regular expression modifiers that alter the execution flow of the application.
The technical exploitation relies on the improper handling of user input within regular expression patterns. When the lastdate parameter contains specially crafted content, it modifies the regular expression behavior by appending the "#e" modifier, which instructs PHP to execute the result of the regular expression as PHP code. This represents a direct violation of input validation principles and demonstrates a dangerous lack of proper sanitization for user-supplied data that is subsequently used in dynamic code execution contexts. The vulnerability maps to CWE-134, which addresses the use of format strings in a context where the format string itself can be modified by an attacker, and more specifically to CWE-94, which covers the execution of arbitrary code due to improper input handling.
The operational impact of this vulnerability is severe as it provides remote code execution capabilities to attackers without requiring authentication or privileged access. Once exploited, attackers can execute arbitrary PHP code on the vulnerable server, potentially leading to complete system compromise, data exfiltration, or deployment of additional malicious payloads. The vulnerability affects widely deployed forum software, making it particularly dangerous in environments where such applications are commonly used for community interaction and content management.
Mitigation strategies should focus on immediate input validation and sanitization of all user-supplied parameters before they are processed in regular expression contexts. The recommended approach includes implementing strict parameter validation, escaping special regex characters in user input, and avoiding the use of dynamic regular expressions that incorporate user data. Organizations should also implement web application firewalls to detect and block suspicious patterns in search parameters, and apply the vendor-provided security patches immediately. From an ATT&CK perspective, this vulnerability aligns with T1059.007 for execution through PHP and T1190 for exploitation of remote services, making it a critical target for defensive measures and network monitoring to prevent unauthorized code execution in web applications.