Due to a vulnerability that’s been discovered in the file Author.pm, it’s imperative that any installation of 2.6 be upgraded immediately.
Download the new Author.pm file here:
And replace the version on your server at lib/MT/Author.pm.
Note: If you have yet upgraded to 2.6, you may disregard this message and upgrade to 2.61 at any time.
[from Mena Trott to the MT-Users mailing list]