CVE-2026-107299
msgpack5: Reserved byte can cause unbounded stream buffering
CVSS Score
5.9
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-228 |
| Vendor | mcollina |
| Product | msgpack5 |
| Published | Oct 8, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
mcollina / msgpack5
< 6.1.0