Secunia

Some vulnerabilities have been reported in phpBB, which can be exploited by malicious people to conduct cross-site scripting and SQL injection attacks, bypass certain security restrictions, and compromise a vulnerable system.

1) Some errors where global variables defined by the user is not properly unset can be exploited in combination with certain input validation errors to execute arbitrary HTML and script code in a user's browser session in context of an affected site. This can also be exploited to manipulate SQL queries by injecting arbitrary SQL code and inject and execute arbitrary PHP code.

Successful exploitation requires that "register_globals" is enabled and that the server runs PHP 5.

The vulnerabilities have been reported in version 2.0.17 and prior.

2) An error in the removing of orphaned entries can be exploited by non moderators to delete shadow topic links.

Successful exploitation requires knowledge of the topic ID for a "shadow topic" entry.

3) An error in the handling of logout requests can be exploited to logout users who views a malicious post containing an "img" BBcode tag referencing a specially crafted URL.

Some other issues which may be security related have also been reported by the vendor.

Solution
Update to version 2.0.18.
Further details available in Customer Area

Provided and/or discovered by
1) Stefan Esser, Hardened-PHP Project
2-3) Reported by vendor

Changelog
Further details available in Customer Area

Original Advisory
1) http://www.hardened-php.net/advisory_172005.75.html

Deep Links
Links available in Customer Area