Versions of lodash.defaultsdeep before 4.6.1 are vulnerable to prototype pollution. The function mergeWith may allow a malicious user to modify the prototype of Object via {constructor: {prototype: {...}}} causing the addition or modification of an existing property that will exist on all objects.

Recommendation

Update to version 4.6.1 or later.

References

• https://www.npmjs.com/advisories/1068