CVE-2026-107302: high-severity vulnerability in mcollina msgpack5
msgpack5: Truncated map32 headers throw an unexpected error
Published
18Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5
exploitation probability
—
observed exploitation
nono source reports it
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the decoder reads the four-byte length of a map32 value before validating that the complete five-byte header is available. A truncated map32 header therefore causes a checked out-of-bounds buffer read and throws RangeError instead of IncompleteBufferError, which can unexpectedly terminate a request, stream, or worker in applications that wait for additional bytes after IncompleteBufferError. There is no adjacent-memory disclosure because the buffer implementation checks bounds. This issue is fixed in version 6.1.0.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
mcollina · msgpack5Related CVEs — mcollina msgpack5
In the same product, most dangerous first.
CVE-2021-21368MEDIUMPrototype poisoningEPSS 1.6%CVE-2026-107301MEDIUMmsgpack5: Partial options disable prototype protectionEPSS —CVE-2026-107300HIGHmsgpack5: Many buffered values can exhaust the streaming decoder stackEPSS —CVE-2026-107299MEDIUMmsgpack5: Reserved byte can cause unbounded stream bufferingEPSS —CVE-2026-107298MEDIUMmsgpack5: Deeply nested input can exhaust the decoder stackEPSS —CVE-2026-107297MEDIUMmsgpack5: Quadratic parsing in the streaming decoderEPSS —