Two vulnerabilities have been reported in TYPO3, which can be exploited by malicious people to conduct cross-site scripting attacks, and by malicious users to compromise a vulnerable system.

1) The vulnerability is caused due to an error in the handling of file uploads, if a filename has multiple file extensions (e.g. "file.php.1") or starts with a dot character (e.g. ".htaccess"). This can be exploited to execute arbitrary code.

Successful exploitation of this vulnerability requires a certain server configuration. It also requires either valid backend user credentials and access to filemounts, or that frontend plugins using "t3lib_div::verifyFilenameAgainstDenyPattern()" or "processFiles()" to handle file uploads are installed.

2) Input passed in unspecified parameters to fe_adminlib.inc is not properly sanitised before being returned to the user. This can be exploited to execute arbitrary HTML and script code in a user's browser session in context of an affected site.

Successful exploitation of this vulnerability requires that a frontend extension based on fe_adminlib.inc is installed - e.g. direct_mail_subscription, feuser_admin, or kb_md5fepw.

The vulnerabilities are reported in all 3.x versions, 4.0.x versions below 4.0.9, 4.1.x versions below 4.1.7, and in 4.2.0.

Solution
Update to version 4.0.9, 4.1.7, or 4.2.1.

Provided and/or discovered by
1) The vendor credits Michiel Roos and Marcus Krause.
2) The vendor credits Christian Seifert, Jeroen van Iddekinge, and Arnd Messer.

Changelog
Further details available to Secunia VIM customers

Original Advisory
TYPO3-20080611-1:
http://typo3.org/teams/security/security-bulletins/typo3-20080611-1/

Deep Links
Links available to Secunia VIM customers