An issue was discovered in json-c from 20200420 (post 0.14 unreleased code) through 0.15-20200726. A stack-buffer-overflow exists in the auxiliary sample program json_parse which is located in the function parseit.
The hash functionality in json-c before 0.12 allows context-dependent attackers to cause a denial of service (CPU consumption) via crafted JSON data, involving collisions.