Cod4 18 Patch Updated
The reason is simple: For years, COD4 used GameSpy technology for its server browser. When GameSpy announced it was shutting down in 2014 (which would have killed all online multiplayer), Activision and Infinity Ward rushed out Patch 1.8 as a stopgap.
The search for "cod4 18 patch" likely refers to two distinct things: the v1.8 update cod4 18 patch