Aranburu was named among the outsiders on the Bretagne Classic 2026 startlist for Cofidis, so a result isn't implausible on paper. But "won after a decisive attack in the final kilometres" is a specific claim that needs a result sheet behind it, and the standard sources — ProCyclingStats' result page for the race — show nothing. Until an official classification or a race report from a recognized outlet appears, this stays a rumor with a plausible name attached, not a confirmed win.