Upgrading to a new version of Windows was apparently not possible, which also means that upgrading to a new Linux version would also have been out of the books.
So the only solution would have been to hire someone to backport whatever fix was needed.
An open source update can be audited much more easily than a closed source update. It is also usually possible, with OSSW, to find the discussion where the software's developers proposed various solutions, and debated their merits and risks.
Upgrading to a new version of Windows was apparently not possible, which also means that upgrading to a new Linux version would also have been out of the books.
So the only solution would have been to hire someone to backport whatever fix was needed.