Secunia

Two vulnerabilities have been reported in Mac OS X, allowing malicious web sites to compromise a vulnerable system.

1) The problem is that the "help" URI handler allows execution of arbitrary local scripts (.scpt) via the classic directory traversal character sequence using "help:runscript".

2) It is also possible to silently place arbitrary files in a known location, including script files, on a user's system using the "disk" URI handler. Files on disk images can be executed without using the "help" URI handler.

Various variants of the URI handler vulnerabilities are currently being discussed.

This has been confirmed on Macintosh OS X using Safari 1.2.1 (v125.1) and Internet Explorer 5.2. Other browsers and applications supporting URI handlers may also be used as attack vectors.

NOTE: The rating has been upgraded to "Extremely Critical" because the issues are very easy to exploit and a large number of working exploits are available.

Solution
Apple has issued patches:
Further details available in Customer Area

Provided and/or discovered by
Various persons and web sites has reported and discussed these issues.

Apple credits lixlpixel and René Puls with the discovery of these issues.

Changelog
Further details available in Customer Area

Original Advisory
http://fundisom.com/owned/warning

Other references
Further details available in Customer Area

Deep Links
Links available in Customer Area