Now don't panic just because of the headline. The bug was introduced in version 5.25, and the update is version 5.25a. The nature of the bug is described in Hartmut (of SkySQL -- cute rhyme) Holzgraefe's blog.
In a table with 2 indexes, this SQL uses up all available disk space.
UPDATE t1 SET id2 = id2 + 1, b = null
WHERE a is null and id1 = 2;
The cause is mysterious and the choices both few and ugly. For a description of them, see http://www.i-programmer.info/news/84/4490.html,
A better idea, of course, is to grab the update as soon as possible. Chances are that the user of 5.25 will still have to restore the datababase on a new server or instance.
Peter Laursen of webYog comments:
"The lack of willingness of Oracle here to expose the exact conditions for this bug to affected users (and how to repair it should they be affected) is the real problem here".