msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder treats the reserved MessagePack byte 0xc1 as incomplete input instead of invalid input. When 0xc1 begins a stream, subsequent data remains buffered while the decoder waits for bytes that cannot make the value valid, allowing a remote peer to exhaust memory. This issue is fixed in version 6.1.0.
https://github.com/mcollina/msgpack5/security/advisories/GHSA-26wq-p25c-j6fv
https://github.com/mcollina/msgpack5/releases/tag/v6.1.0
https://github.com/mcollina/msgpack5/commit/85da345bf1acc18ca441741e5cf4aa0ed0d69314