Description
merge-deep node module before 3.0.1 suffers from a Modification of Assumed-Immutable Data (MAID) vulnerability, which allows a malicious user to modify the prototype of "Object" via __proto__, causing the addition or modification of an existing property that will exist on all objects.
Remediation
References
https://hackerone.com/reports/310708
https://github.com/jonschlinkert/merge-deep/commit/2c33634da7129a5aefcc262d2fec2e72224404e5