UltraJSON (aka ujson) through 5.1.0 has a stack-based buffer overflow in Buffer_AppendIndentUnchecked (called from encode). Exploitation can, for example, use a large amount of indentation.
https://lists.debian.org/debian-lts-announce/2022/02/msg00023.html
https://github.com/ultrajson/ultrajson/pull/504
https://github.com/ultrajson/ultrajson/issues/502#issuecomment-1031747284
https://github.com/ultrajson/ultrajson/issues/501
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/ujson/OSV-2021-955.yaml