Heap overflow

A heap-based buffer overflow issue was discovered in libjpeg-turbo in h2v2_merged_upsample_internal() function of jdmrgext.c file. The vulnerability can only be exploited with 12-bit data precision for which the range of the sample data type exceeds the valid sample range, hence, an attacker could craft a 12-bit lossless JPEG image that contains out-of-range 12-bit samples. An application attempting to decompress such image using merged upsampling would lead to segmentation fault or buffer overflows, causing an application to crash.