How much does a “Potion of cure light wounds” heal?

According to the documentation, a potion of cure light wounds points to the spell “cure light wounds”. Now, the spell has some info about healing:

cures 1d8 points of damage +1 point per caster level (maximum +5)

But the caster level is just for the cleric who casts the spell. So what would be the correct amount of healing with the potion alone? just 1d8? or 1d8+5?

I could not find any clearer documentation for the potion yet.