member.php in MyBB (aka MyBulletinBoard) before 1.4.12 makes a certain superfluous call to the SQL COUNT function, which allows remote attackers to cause a denial of service (resource consumption) by making requests to member.php that trigger scans of the entire users table.
MyBB (aka MyBulletinBoard) before 1.4.12 does not properly restrict uid values for group join requests, which allows remote attackers to cause a denial of service (resource consumption) by using guest access to submit join request forms for moderated groups, related to usercp.php and managegroup.php.
Cross-site scripting (XSS) vulnerability in the redirect function in functions.php in MyBB (aka MyBulletinBoard) 1.4.2 allows remote attackers to inject arbitrary web script or HTML via the url parameter in a removesubscriptions action to moderation.php, related to use of the ajax option to request a JavaScript redirect. NOTE: this can be leveraged to execute PHP code and bypass cross-site request forgery (CSRF) protection.
MyBB (aka MyBulletinBoard) 1.4.2 uses insufficient randomness to compose filenames of uploaded files used as attachments, which makes it easier for remote attackers to read these files by guessing filenames.
MyBB (aka MyBulletinBoard) 1.4.2 does not properly handle an uploaded file with a nonstandard file type that contains HTML sequences, which allows remote attackers to cause that file to be processed as HTML by Internet Explorer's content inspection, aka "Incomplete protection against MIME-sniffing." NOTE: this could be leveraged for XSS and other attacks.
SQL injection vulnerability in misc.php in MyBB (aka MyBulletinBoard) before 1.4.1 allows remote attackers to execute arbitrary SQL commands via a certain editor field.
Multiple cross-site scripting (XSS) vulnerabilities in MyBB (aka MyBulletinBoard) before 1.4.1 allow remote attackers to inject arbitrary web script or HTML via (1) a certain referrer field in usercp2.php, (2) a certain location field in inc/functions_online.php, and certain (3) tsubject and (4) psubject fields in moderation.php.
moderation.php in MyBB (aka MyBulletinBoard) before 1.4.1 does not properly check for moderator privileges, which has unknown impact and remote attack vectors.
Cross-site scripting (XSS) vulnerability in MyBB 1.2.x before 1.2.14 allows remote attackers to inject arbitrary web script or HTML via unspecified vectors, possibly involving search.php.
Multiple cross-site scripting (XSS) vulnerabilities in MyBB before 1.2.13 allow remote attackers to inject arbitrary web script or HTML via unspecified parameters to (1) portal.php and (2) inc/functions_post.php.