Abbreviation for current
Solution 1:
cur.
Just add a period to hint that it is an abbreviation.
See http://www.thefreedictionary.com/cur:
- currency.
- current.
Solution 2:
When coding, I've typically used curr to match the length of the names of the next and prev variables that are usually also involved, e.g.
void *next = NULL;
void *prev = NULL;
void *curr = NULL;