CVE-2026-59879: Immutable.js `List` 32-bit trie overflow → unrecoverable DoS

List#set, List#setSize, List#setIn, List#updateIn (and the functional set / setIn / updateIn) mishandle an index or size in the range [2 ** 30, 2 ** 31):

• On an empty List the operation enters an uncatchable infinite loop (a tight CPU spin; a surrounding try/catch never regains control). Only killing the worker recovers it.
• On a populated List (≥ 32 elements — i.e. any array of ≥ 32 items turned into a List by fromJS) the loop allocates without bound → heap exhaustion → the process aborts (SIGABRT, exit 134, or kernel OOM-kill 137). A real crash, not a recoverable error.

The index may be a numeric string, so it can come straight from a request body, URL, or key-path. A single small unauthenticated request is enough.

There is also a companion silent data-corruption issue in setSize:

List([1, 2, 3]).setSize(2 ** 31); // before fix => size 0  (silently cleared)
List([1, 2, 3]).setSize(2 ** 32 + 5); // before fix => size 5  (huge value wraps to 5)