CVE-2026-107297 (CVSS 5.9)

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.

Is your site exposed to CVE-2026-107297?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

5.9

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0039

Probability of exploitation

0.31%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-407 CWE-407

References

Other References

https://github.com/mcollina/msgpack5/commit/e4827641d3105e295cbbd56e9c5389978547eab4 https://github.com/mcollina/msgpack5/releases/tag/v6.1.0 https://github.com/mcollina/msgpack5/security/advisories/GHSA-gcx5-hxj7-gpqq

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 5.9 (MEDIUM).

How severe is CVE-2026-107297? +

CVE-2026-107297 has a CVSS v3.1 score of 5.9 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0039, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-107297? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-43967

Inefficient Algorithmic Complexity vulnerability in absinthe-graphql absinthe allows unauthenticated denial of service via quadratic fragment-name uniqueness validation. 'Elixir.Absinthe.Phase.Document.Validation.UniqueFragmentNames':run/2 iterates over …

CVE-2026-58059

In Bouncy Castle for Java before 1.85, Quadratic-time escaping when stringifying X.500 distinguished names. This issue also affects Bouncy Castle …

CVE-2026-3276

unicodedata.normalize() can take excessive CPU time when processing specially crafted Unicode input containing long runs of combining characters with alternating …

CVE-2026-40476

graphql-go is a Go implementation of GraphQL. In versions 15.31.4 and below, the OverlappingFieldsCanBeMerged validation rule performs O(n²) pairwise comparisons …

CVE-2026-13149

brace-expansion through 5.0.6 is vulnerable to denial of service. The expand() function exhibits exponential-time complexity in the number of consecutive …

CVE-2026-94658

Inefficient Algorithmic Complexity vulnerability in Apache Thrift Lua bindings. This issue affects Apache Thrift: before 0.25.0. Users are recommended to …

CVE-2026-107297