CVE-2026-107297: medium-severity vulnerability in mcollina msgpack5
msgpack5: Quadratic parsing in the streaming decoder
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 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.
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-2026-107299MEDIUMmsgpack5: Reserved byte can cause unbounded stream bufferingEPSS —CVE-2026-107298MEDIUMmsgpack5: Deeply nested input can exhaust the decoder stackEPSS —