CVE-2026-124540

JSON::XS versions before 4.05 for Perl allow stack exhaustion via nested tagged values under allow tags in decode tag.

With allow tags, "(" starts a tagged value. Its tag and value are decoded recursively, and each can start another tagged value. Unlike arrays and objects, this nesting is not counted against max depth.

A run of "(" bytes exhausts the C stack and triggers an uncatchable segmentation fault regardless of max depth.