UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 6-K Report of Foreign Issuer Pursuant To Rule 13a-16 Or 15d-16 of the Securities Exchange Act of 1934 For the month of August 2025 Commission File Number: 333-251238 Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): COSAN S.A. (Exact name of registrant as specified in its charter) N/A (Translation of registrant's name into English) Yes ☐ No ☒ Av. Brigadeiro F ...