Debian: CVE-2021-21843: gpac -- security update

Multiple exploitable integer overflow vulnerabilities exist within the MPEG-4 decoding functionality of the GPAC Project on Advanced Content library v1.0.1. A specially crafted MPEG-4 input can cause an integer overflow due to unchecked arithmetic resulting in a heap-based buffer overflow that causes memory corruption. After validating the number of ranges, at [41] the library will multiply the count by the size of the GF_SubsegmentRangeInfo structure. On a 32-bit platform, this multiplication can result in an integer overflow causing the space of the array being allocated to be less than expected. An attacker can convince a user to open a video to trigger this vulnerability.