New Firefox 3.0.9 patches mucked-up memory and other holes
There are multiple bugs, according to the Mozilla security advisory (MFSA 2009-14), and the crashes they caused demonstrated memory corruption under certain circumstances.
That's the only critical-level problem meriting a patch in the latest edition of Firefox; by contrast, the 3.0.8 release nailed down two, one of which (an XSL stylesheet problem) also affected SeaMonkey. The other, which allowed arbitrary code execution through the XUL <tree> element, was the vulnerability that owned up Firefox at this year's CanSecWest Pwn2Own contest. Nothing so glamorous this time around, for fans of the big splashy bugs.