Is CVE-2026-107299 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-107299?

CVE-2026-107299 has a CVSS v3 severity of MEDIUM (5.9).

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CVE-2026-107299

Description

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.