GHSA-3jw5-9pmw-vmfg: GPAC MP4Box Heap Buffer Overflow Write in gf_xml_parse_bit_sequence_bs (NHML BS Parsing)

GPAC is an open-source multimedia framework. Prior to commit 86b0e36, a heap-based buffer overflow (write) vulnerability was discovered in GPAC MP4Box. The vulnerability exists in the gfxmlparsebitsequencebs function in utils/xmlbincustom.c when processing a crafted NHML file containing malicious <BS> (BitSequence) elements. An attacker can exploit this by providing a specially crafted NHML file, causing an out-of-bounds write on the heap. This issue has been via commit 86b0e36.