v4.18.0

Security

_.unset / _.omit: Fixed prototype pollution via constructor/prototype path traversal (GHSA-f23m-r3pf-42rh, fe8d32e). Previously, array-wrapped path segments and primitive roots could bypass the existing guards, allowing deletion of properties from built-in prototypes. Now constructor and prototype are blocked unconditionally as non-terminal path keys, matching baseSet. Calls that previously returned true and deleted the property now return false and leave the target untouched.

_.template: Fixed code injection via imports keys (GHSA-r5fr-rjxr-66jc, CVE-2026-4800, 879aaa9). Fixes an incomplete patch for CVE-2021-23337. The variable option was validated against reForbiddenIdentifierChars but importsKeys was left unguarded, allowing code injection via the same Function() constructor sink. imports keys containing forbidden identifier characters now throw "Invalid imports option passed into _.template".

Docs

• Add security notice for _.template in threat model and API docs (#6099)
• Document lower > upper behavior in _.random (#6115)
• Fix quotes in _.compact jsdoc (#6090)