The mark_context_stack function in gc.c in mruby through 1.2.0 allows attackers to cause a denial of service (heap-based use-after-free and application crash) or possibly have unspecified other impact via a crafted .rb file.
https://lists.debian.org/debian-lts-announce/2022/05/msg00006.html
https://github.com/mruby/mruby/commit/5c114c91d4ff31859fcd84cf8bf349b737b90d99