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[ CVE-2026-107297 · Published 8 Oct 2026 ]

msgpack5: Quadratic parsing in the streaming decoder

CVSS 5.9 EPSS <1%Fix available

[ Description ]Official description

msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder reparses an incomplete array or map from the beginning whenever another chunk arrives. A remote peer can split one valid MessagePack container across many small chunks, causing completed elements to be decoded repeatedly, producing quadratic CPU use and blocking the event loop. This issue is fixed in version 6.1.0.

[ Fixes ]Fixes and patches

  • msgpack5 6.1.0Fixed version · GitHub Advisories · npm package msgpack5: upgrade to 6.1.0 or later (affected < 6.1.0)

[ Packages ]Affected open-source packages

[ References ]References