CVSS 4.0
8.7 highCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:NCVE-2026-93753
High (8.7). EPSS 0.5% chance of exploitation in the next 30 days.
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.
Severity
CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N- EPSS
- 0.5% chance of exploitation in the next 30 days; higher than 43% of CVEs (scores of 2026-10-31)
- CWE
- CWE-1321
- Published
- Modified
- Record from
- the NVD, synced
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-gcqx-w48m-w2h4 | npm | deepmerge | >=4.2.0 <=4.3.1 | no fix published |
References
- 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
- https://github.com/TehShrike/deepmerge/issues/273