DISPUTED QueryString.php in Simple Machines Forum (SMF) 1.0.7 and earlier, and 1.1rc2 and earlier, allows remote attackers to more easily spoof the IP address and evade banning via a modified X-Forwarded-For HTTP header, which is preferred instead of other more reliable sources for the IP address. NOTE: the original researcher claims that the vendor has disputed this issue.

Cross-site scripting (XSS) vulnerability in index.php in Simple Machines Forum (SMF) allows remote attackers to inject arbitrary web script or HTML via a base64 encoded params value in the action parameter.

Cross-site scripting (XSS) vulnerability in index.php in Simple Machines Forum (SMF) 1.1 RC2 allows remote attackers to inject arbitrary web script or HTML via the action parameter.

Simple Machines Forum (SMF) 1.1RCx before 1.1RC3, and 1.0.x before 1.0.8, does not properly unset variables when the input data includes a numeric parameter with a value matching an alphanumeric parameter's hash value, which allows remote attackers to perform directory traversal attacks to read arbitrary local files, lock topics, and possibly have other security impacts. NOTE: it could be argued that this vulnerability is due to a bug in the unset PHP command (CVE-2006-3017) and the proper fix should be in PHP; if so, then this should not be treated as a vulnerability in Simple Machines Forum.