PANS-ATM 8.5.6.2 says: "When necessary, the minimum radar vectoring altitude shall include a correction for low temperature effect" with a further note that it is the responsibility of the ATS authority to provide the controller with this data.
In the UK, while MATS Part1 does not explicitly mention low temp correction, the phrasing used suggests that it would be an ATC responsibility
"Controllers are to ensure that levels assigned to:
a) IFR flights in receipt of a Radar Control Service
b) flights in receipt of a RAS and
c) flights in receipt of a RIS and receiving vectors;
provide adequate terrain clearance for the phase of flight as shown below."
I would be surprised if the MATS Part 2 for units/aerodromes where terrain is an issue does not include some provision for this. E.g. Inverness has been ISA -20 degC on the surface for a while now. It has a minimum altitude chart with 5600 ft not far away. That's about 5200 ft true in ISA -20, though in reality there's an inversion so the true altitude is likely to be more like 5400 ft. That's still going to keep you above Ben Macdui, but it is significant.