CVE-2026-107299: medium-severity vulnerability in mcollina msgpack5
msgpack5: Reserved byte can cause unbounded stream buffering
Published
10Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 5.9
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 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.
CVSS:3.1/AV:N/AC:H/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-2026-107302HIGHmsgpack5: Truncated map32 headers throw an unexpected errorEPSS —CVE-2026-107301MEDIUMmsgpack5: Partial options disable prototype protectionEPSS —CVE-2026-107300HIGHmsgpack5: Many buffered values can exhaust the streaming decoder stackEPSS —CVE-2026-107298MEDIUMmsgpack5: Deeply nested input can exhaust the decoder stackEPSS —CVE-2026-107297MEDIUMmsgpack5: Quadratic parsing in the streaming decoderEPSS —