Secunia

A weakness and a vulnerability have been discovered in phpBB, which can be exploited by malicious users to compromise a vulnerable system and by malicious people to use it for making HTTP requests to other sites.

1) A design error in the "Upload Avatar from a URL" functionality can be exploited to cause the server to make HTTP GET requests to arbitrary remote sites.

Successful exploitation requires that the "Enable avatar uploading" setting is enabled (disabled by default).

2) Input passed to the "Font Colour 3" field isn't properly sanitised before being used in a "preg_replace()" call with the "e" modifier. This can be exploited to inject and execute arbitrary PHP code.

Successful exploitation requires administrative privileges.

The weakness and the vulnerability have been confirmed in version 2.0.20. Other versions may also be affected.

Solution
Update to version 2.0.21.
Further details available in Customer Area

Provided and/or discovered by
1) rgod
2) noch22

Changelog
Further details available in Customer Area

Deep Links
Links available in Customer Area