Array index error in the (1) dtoa implementation in dtoa.c (aka pdtoa.c) and the (2) gdtoa (aka new dtoa) implementation in gdtoa/misc.c in libc, as used in multiple operating systems and products including in FreeBSD 6.4 and 7.2, NetBSD 5.0, OpenBSD 4.5, Mozilla Firefox 3.0.x before 3.0.15 and 3.5.x before 3.5.4, K-Meleon 1.5.3, SeaMonkey 1.1.8, and other products, allows context-dependent attackers to cause a denial of service (application crash) and possibly execute arbitrary code via a large precision value in the format argument to a printf function, which triggers incorrect memory allocation and a heap-based buffer overflow during conversion to a floating-point number.
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.