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msgpack5: Deeply nested input can exhaust the decoder stack

Moderate severity GitHub Reviewed Published Sep 26, 2026 in mcollina/msgpack5 • Updated Oct 8, 2026

Package

npm msgpack5 (npm)

Affected versions

< 6.1.0

Patched versions

6.1.0

Description

Impact

The decoder has no nesting-depth limit for arrays and maps. An attacker who can provide MessagePack input can use deeply nested containers to exhaust the JavaScript call stack and interrupt the process or request handler.

Patches

The decoder now limits nesting depth to 100 by default and throws Maximum decode depth exceeded. Applications can configure the limit with the maxDepth option.

Workarounds

Reject deeply nested input before decoding, isolate decoding in a worker, or enforce a trusted schema with a bounded nesting depth.

References

@mcollina mcollina published to mcollina/msgpack5 Sep 26, 2026
Published to the GitHub Advisory Database Oct 8, 2026
Reviewed Oct 8, 2026
Last updated Oct 8, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(29th percentile)

Weaknesses

Uncontrolled Recursion

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack. Learn more on MITRE.

CVE ID

CVE-2026-107298

GHSA ID

GHSA-24ch-f2g6-9hhh

Source code

Credits

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