Although the update is not really a security fix, crashes, such as the OS X font problem in OS X 10.7, always imply some security risk, said Paul Ducklin, Sophos head of technology, Asia Pacific.
"Whenever a program takes an uncharted and unexpected path of execution, there is cause for concern," he wrote in a blog post.
Ducklin said it is good to see that Mozilla is willing to produce this sort "between-the-train-stations" release, despite the fact that version 6 is due relatively soon in mid-August.
This story was first published by Computer Weekly