What is CVE-2026-107297?

CVE-2026-107297 is a medium-severity vulnerability in Mcollina Msgpack5, classified under Inefficient Algorithmic Complexity. CVSS score: 5.9/10. Published 2026-10-08.

How severe is CVE-2026-107297?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Mcollina Msgpack5

CVE-2026-107297

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.

Published 2026-10-08 · last modified 2026-10-08.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/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

Mcollina Msgpack5 — versions < 6.1.0

Weakness classification (CWE)

CWE-407 — Inefficient Algorithmic Complexity

References

Frequently asked questions

What is CVE-2026-107297?: CVE-2026-107297 is a medium-severity vulnerability in Mcollina Msgpack5, classified under Inefficient Algorithmic Complexity. CVSS score: 5.9/10. Published 2026-10-08.
How severe is CVE-2026-107297?: Medium severity. CVSS v3 base score is 5.9 out of 10.