deepmerge through 4.3.1 Prototype Poisoning via mergeObject

These records connect through source-stated identifiers. Shared identifiers or dates alone do not establish shared exposure, root cause or applicability.

CVE-2026-93753 · Microsoft / collected KEV context

EUVD-2026-83258

GHSA-gcqx-w48m-w2h4

cve-program · CVE-2026-93753

• https://github.com/TehShrike/deepmerge/issues/273
• https://github.com/TehShrike/deepmerge
• https://github.com/TehShrike/deepmerge/blob/5b87756a5671635679001cbac72aa42f23472c81/index.js#L39-L60
• https://www.vulncheck.com/advisories/deepmerge-through-4.3.1-prototype-poisoning-via-mergeobject

euvd · EUVD-2026-83258

• https://github.com/TehShrike/deepmerge/issues/273
• https://github.com/TehShrike/deepmerge
• https://github.com/TehShrike/deepmerge/blob/5b87756a5671635679001cbac72aa42f23472c81/index.js#L39-L60
• https://www.vulncheck.com/advisories/deepmerge-through-4.3.1-prototype-poisoning-via-mergeobject

nvd · CVE-2026-93753

• https://github.com/TehShrike/deepmerge
• https://github.com/TehShrike/deepmerge/blob/5b87756a5671635679001cbac72aa42f23472c81/index.js#L39-L60
• https://github.com/TehShrike/deepmerge/issues/273
• https://www.vulncheck.com/advisories/deepmerge-through-4.3.1-prototype-poisoning-via-mergeobject

osv · GHSA-gcqx-w48m-w2h4

• https://nvd.nist.gov/vuln/detail/CVE-2026-93753
• https://github.com/TehShrike/deepmerge/issues/273
• https://github.com/TehShrike/deepmerge
• https://github.com/TehShrike/deepmerge/blob/5b87756a5671635679001cbac72aa42f23472c81/index.js#L39-L60
• https://www.vulncheck.com/advisories/deepmerge-through-4.3.1-prototype-poisoning-via-mergeobject

• 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 in… · Advisory content revised · 30 Oct 2026
• deepmerge mergeObject() allows prototype poisoning of returned objects · Newly collected advisory · 27 Oct 2026