Simple Machines Forum (SMF) before 1.1.19 and 2.x before 2.0.6 allows remote attackers to impersonate arbitrary users via multiple space characters characters.

Simple Machines Forum (SMF) 2.0.6, 1.1.19, and earlier allows remote attackers to impersonate arbitrary users via a Unicode homoglyph character in a username.

Simple Machines Forum (SMF) before 1.1.19 and 2.x before 2.0.6 allows remote attackers to conduct clickjacking attacks via an X-Frame-Options header.

Unrestricted file upload vulnerability in the avatar upload functionality in Simple Machines Forum before 2.0.6 and 2.1 allows remote authenticated users to execute arbitrary code by uploading a file with an executable extension, then accessing it via a direct request to the file in an unspecified directory.

Directory traversal vulnerability in index.php in Simple Machines Forum (SMF) 1.0 before 1.0.15 and 1.1 before 1.1.7 allows remote authenticated users to configure arbitrary local files for execution via directory traversal sequences in the value of the theme_dir field during a jsoption action, related to Sources/QueryString.php and Sources/Themes.php, as demonstrated by a local .gif file in attachments/ with PHP code that was uploaded through a profile2 action to index.php.

Directory traversal vulnerability in index.php in Simple Machines Forum (SMF) 1.0 before 1.0.15 and 1.1 before 1.1.7 allows remote authenticated administrators to install packages from arbitrary directories via a .. (dot dot) in the package parameter during an install2 action, as demonstrated by a predictable package filename in attachments/ that was uploaded through a post2 action to index.php.

Cross-site request forgery (CSRF) vulnerability in index.php in Simple Machines Forum (SMF) 1.0 before 1.0.15 and 1.1 before 1.1.7 allows remote attackers to hijack the authentication of admins for requests that install packages via the package parameter in an install2 action.

Multiple PHP remote file inclusion vulnerabilities in Simple Machines Forum (SMF) 1.1.4 allow remote attackers to execute arbitrary PHP code via a URL in the (1) settings[default_theme_dir] parameter to Sources/Subs-Graphics.php and (2) settings[default_theme_dir] parameter to Sources/Themes.php. NOTE: CVE and multiple third parties dispute this issue because the files contain a protection mechanism against direct request

Simple Machines Forum (SMF) 1.1.4 allows remote attackers to read a message in private forums by using the advanced search module with the "show results as messages" option, then searching for possible keywords contained in that message.