GitHub Advisoryadvisory · npm
GHSA-gcqx-w48m-w2h4 deepmerge mergeObject() allows prototype poisoning of returned objects
LOW
Official page ↗
- Aliases
- CVE-2026-93753
- Ecosystem
- npm
- Packages
- deepmerge
- Severity
- Low
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- Weaknesses
- CWE-1321
- Reviewed
- 2026-10-27
Affected packages
• npm deepmerge: >= 4.2.0, <= 4.3.1 (no fix yet)
Description
deepmerge through 4.3.1 contains a prototype poisoning vulnerability in the mergeObject() function that fails to properly validate keys being written to target objects. Attackers can supply malicious source objects in merge operations to inject attacker-controlled properties into the returned object's prototype, causing applications to inherit unintended values when accessing properties without own-property checks.
Related
Alias · not in database (1)
Weakness · CWE (1)
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes weakness
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-93753 advisory
- https://github.com/TehShrike/deepmerge/issues/273 web
- https://github.com/TehShrike/deepmerge package
- https://github.com/TehShrike/deepmerge/blob/5b87756a5671635679001cbac72aa42f23472c81/index.js#L39-L60 web
- https://www.vulncheck.com/advisories/deepmerge-through-4.3.1-prototype-poisoning-via-mergeobject web