Description
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.
Published: 2026-10-08
Score: 5.9 Medium
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-26wq-p25c-j6fv msgpack5: Reserved byte can cause unbounded stream buffering
History

Thu, 08 Oct 2026 17:15:00 +0000

Type Values Removed Values Added
Description 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.
Title msgpack5: Reserved byte can cause unbounded stream buffering
Weaknesses CWE-228
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-08T17:09:47.191Z

Reserved: 2026-10-07T15:53:23.587Z

Link: CVE-2026-107299

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-08T17:17:15.850

Modified: 2026-10-08T17:17:15.850

Link: CVE-2026-107299

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-08T19:00:07Z

Weaknesses