Directory traversal vulnerability in Yet another Bulletin Board (YaBB) 2.1 and earlier allows remote authenticated users to execute arbitrary Perl code via a .. (dot dot) in the userlanguage profile setting, which sets the userlanguage key of the member hash, and is propagated to the language variable in (1) HelpCentre.pl and (2) ICQPager.pl, (3) the use_lang variable in Subs.pl, and the actlang variable in (4) Post.pl and (5) InstantMessage.pl; as demonstrated by pointing userlanguage to the English folder, modifying English/HelpCentre.lng file to contain Perl statements, and then invoking the help action in YaBB.pl.

Interpretation conflict in YaBB before 2.1 allows remote authenticated users to inject arbitrary web script or HTML via HTML in a file with a GIF file extension, which causes the HTML to be executed by a victim who views the file in Internet Explorer as a result of CVE-2005-3312. NOTE: it could be argued that this vulnerability is due to a design flaw in Internet Explorer and the proper fix should be in that browser; if so, then this should not be treated as a vulnerability in YaBB.

Cross-site scripting (XSS) vulnerability in usersrecentposts in YaBB 2.0 rc1 allows remote attackers to inject arbitrary web script or HTML via the username parameter.

Cross-site scripting (XSS) vulnerability in YaBB.pl for YaBB 2.0 RC1 allows remote attackers to inject arbitrary web script or HTML via the username parameter in a usersrecentposts action.