CVE-2026-54737
Received Received - Intake

Prototype Pollution in @phun-ky/defaults-deep Library

Publication date: 2026-07-31

Last updated on: 2026-07-31

Assigner: GitHub, Inc.

Description
@phun-ky/defaults-deep is a library like lodash defaultsDeep with array preservation and no lodash dependency. Prior to 2.0.5, defaultsDeep() recursively merges user-supplied objects without filtering proto, constructor, and prototype, allowing properties to be written to Object.prototype. This issue is fixed in version 2.0.5.

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Meta Information

Published
2026-07-31
Last Modified
2026-07-31
Generated
2026-07-31
AI Q&A
2026-07-31
EPSS Evaluated
N/A
NVD
CVE-2026-54737
EUVD
EUVD-2026-51592

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
phun-ky defaults_deep to 2.0.5 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-1321 The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.

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Executive Summary

This vulnerability affects the @phun-ky/defaults-deep library before version 2.0.5. The function defaultsDeep() merges objects recursively but fails to filter proto, constructor, and prototype properties. This allows attackers to write to Object.prototype, potentially altering object behavior globally.

Detection Guidance

This vulnerability can be detected by checking the version of @phun-ky/defaults-deep in your project. If the version is below 2.0.5, the system is vulnerable. Use commands like 'npm list @phun-ky/defaults-deep' or check your package.json file.

Impact Analysis

An attacker could exploit this to modify Object.prototype, causing unexpected behavior in applications using the vulnerable library. This may lead to crashes, data corruption, or unintended code execution in affected systems.

Mitigation Strategies

Immediately update @phun-ky/defaults-deep to version 2.0.5 or later. Review code for potential prototype pollution issues and sanitize user inputs to prevent malicious property assignments.

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