CVE-2026-124539

JSON::XS versions before 4.05 for Perl leak the decoded key of an object rejected for a missing colon in decode_hv.

Unless it is short plain ASCII, a quoted key is decoded into a new scalar. Nothing frees that scalar when the object is rejected for a missing ':' after the key.

A process that keeps running after a failed decode retains one key per rejected document, with its size chosen by the sender. Repeated requests exhaust process memory.