Mojo::JSON versions before 9.47 for Perl allow memory exhaustion via unbounded recursion in the pure-Perl decoder. The pure-Perl decode path (`_decode_value` dispatching to `_decode_array` and `_decode_object`) recurses with no depth limit, so a small deeply nested JSON document can consume excessive memory. This path is the default when Cpanel::JSON::XS is not installed or `MOJO_NO_JSON_XS=1` is set; the Cpanel::JSON::XS fast path is not affected. Any caller that decodes an untrusted JSON body, for example `Mojo::Message::json` reached through `$c->req->json`, can exhaust process memory and cause denial of service.
Mojo::JSON versions before 9.47 for Perl allow memory exhaustion via unbounded recursion in the pure-Perl decoder