CVE-2026-51807 [CRITICAL] – Heap-based out-of-bounds write in j2k_precinct_subband::parse_packet_header() in OpenHTJ2K

Heap-based out-of-bounds write in j2k_precinct_subband::parse_packet_header() in OpenHTJ2K versions 0.18.3 and earlier (fixed in v0.18.4) caused by missing bounds validation before coding-pass lengths are written to j2k_codeblock::pass_length[128]. A crafted JPEG 2000 codestream containing malformed PPM packet headers can trigger a heap-based out-of-bounds write in j2k_precinct_subband::parse_packet_header() in source/core/coding/coding_units.cpp due to missing bounds validation for the j2k_codeblock::pass_length[128] array which can lead to heap corruption and process termination.