CVE-2026-107297
Medium
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.
SeverityMedium
CVSS5.9
Exploit probability—
ProductMsgpack5
PublishedOct 8, 2026
First seenOct 8, 2026
Weakness typeCWE-407CWE-407
How to fix
Update
- msgpack56.1.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| msgpack5npm | v < 6.1.0 | 6.1.0 |
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