All vulnerabilities
CVE-2026-93753GHSA-gcqx-w48m-w2h4

deepmerge mergeObject() allows prototype poisoning of returned objects

TehShrike deepmergenpmLibraries & packages
Open in ThreatlineRecord JSON
CVSS
2.7Low
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 18 Sep 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.51%Chance of exploitation activity in the next 30 days, higher than 43% of CVEs. Scored 27 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Published18 Sep 2026Updated 27 Oct 2026CVE List

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

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.

Text from CVE List

Affected versions 3

  • deepmerge, npm>= 4.2.0, <= 4.3.1GitHub
  • deepmergeaffected: all versions through 4.3.1CVE List
  • deepmerge, npmfrom 4.2.0, through 4.3.1OSV

References 6