The vfprintf function in stdio-common/vfprintf.c in GNU C Library (aka glibc) 2.5, 2.12, and probably other versions does not properly restrict the use of the alloca function when allocating the SPECS array, which allows context-dependent attackers to bypass the FORTIFY_SOURCE format-string protection mechanism and cause a denial of service (crash) or possibly execute arbitrary code via a crafted format string using positional parameters and a large number of format specifiers, a different vulnerability than CVE-2012-3404 and CVE-2012-3405. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2012-3406
