GHSA-gcqx-w48m-w2h4 json
deepmerge mergeObject() allows prototype poisoning of returned objects
published last mo. modified 17d ago also CVE-2026-93753
- cvss
- 5.3
- version 3.1, GitHub
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- —
- no score, EPSS covers CVEs only
- public exploits
- 0
- none known
Summary
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.
Is GHSA-gcqx-w48m-w2h4 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| GitHub | 3.1 | 5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| npm | deepmerge | >=4.2.0, <=4.3.1 |
no fix listed |
Classification
- Weakness
-
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes
References
-
nvd.nist.gov
/vuln/detail/CVE-2026-93753
advisory
-
github.com
/TehShrike/deepmerge/issues/273
web
-
github.com
/TehShrike/deepmerge
package
-
github.com
/TehShrike/deepmerge/blob/5b87756a5671635679001cbac72aa42f23472c81/index.js#L39-L60
web
-
vulncheck.com
/advisories/deepmerge-through-4.3.1-prototype-poisoning-via-mergeobject
web
Sources
- GitHub Advisory GHSA-gcqx-w48m-w2h4
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