CVE-2026-93753
High
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.
SeverityHigh
CVSS7.5
Exploit probability—
ProductDeepmerge
PublishedSep 18, 2026
First seenSep 18, 2026
How to fix
Sources list no fixed version or patch link for this vulnerability.
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| deepmergenpm | 4.2.0 ≤ v ≤ 4.3.1 | — |
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