CVE-2026-88351

Critical severity, CVSS 9.8. EPSS: 0.3% chance of exploitation in the next 30 days.

An integer overflow vulnerability exists in the MPack Node API in MPack 1.1.1 on 32-bit platforms. When parsing a specially crafted MessagePack array32 or map32 object with an excessively large element count, the page allocation size calculation in mpack_tree_parse_children() can overflow size_t and produce an undersized allocation. Subsequent parsing writes mpack_node_data_t records beyond the allocated heap buffer, resulting in heap-buffer-overflow, memory corruption, and denial of service.

Published 2026-09-24. Last modified 2026-09-25.