For example VZLUSAT-1 is 5 years old and it is still working.
Under the specific CubeSat design specification, one of the earliest CubeSat launches was on 30 June 2003 from Plesetsk, Russia, with Eurockot Launch Services's Multiple Orbit Mission. The CubeSats were injected into a Sun-synchronous orbit and included the Danish AAU CubeSat and DTUSat, the Japanese XI-IV and CUTE-1, the Canadian Can X-1, and the US Quakesat.
The first mission was a multiple launch of 6 CubeSats using a Rokot-KM rocket, a remake of the old SS-19 Stiletto soviet intercontinental ballistic missile. The CubeSats were: AAU-Cubesat Aalborg University Cubesat (DK), CanX 1 Canadian Advanced Nanospace eXperiments (CA), CUTE 1 CUbical Tokyo institute of technology Engineering satellite (JP), DTUSat Danmarks Tekniske Universitet Satellite (DK), QuakeSat (USA) and XI-IV (JP).
CubeSat XI-IV (Sai Four), the OSCAR 57, is still active.
CUTE-1 is also considered still active.
As of 2022, makes these 2 the oldest CubeSats still active.