Vector boson scattering (VBS) offers a unique window into the electroweak sector and the mechanism of electroweak symmetry breaking. The CMS experiment has performed increasingly precise measurements of VBS processes, exploring complex and previously inaccessible final states, thereby significantly improving our understanding of these rare electroweak interactions. In this seminar, I will review recent CMS VBS measurements and discuss the main experimental challenges and analysis strategies employed to isolate these processes, with particular emphasis on the new combination of VBS measurements with fully leptonic and semi-leptonic final states using LHC Run 2 data. Finally, I will discuss the sensitivity of VBS to the indirect presence of physics beyond the Standard Model in the framework of Effective Field Theory (EFT) and its role in future global fits.