Vulnerability in Mcollina Msgpack5

CVE-2026-107300

msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the value count, exhausting the JavaScript call stack, and interrupting the process or stream. This issue is fixed in version 6.1.0.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-107300?
CVE-2026-107300 is a high-severity vulnerability in Mcollina Msgpack5, classified under Uncontrolled Recursion. CVSS score: 7.5/10. Published 2026-10-08.
How severe is CVE-2026-107300?
High severity. CVSS v3 base score is 7.5 out of 10.