BUT, MS-10 didn't achieve orbit. Successful escape system test though.
So, then I believe it stretches out to 17 months, 26 days. Yuri Gidzenko flew on TM-31: 10/30/00 and TM-34: 4/25/02. Yury Lonchakov is a close Russian second with 18 months 10 days. Space Shuttle 104: 4/19/01 and Soyuz TMA-1: 10/29/02.
I think this is correct. Can anyone confirm?