The woman was attacked by a man in West Hill between 0130 and 0230 GMT on Friday.
Earlier, at 0930 GMT, two teenage girls called police after being followed by a man in Chantilly Way. Police believe the two incidents may be linked.
The suspect is described as a white man aged in his 50s or 60s, who spoke with a London accent. He was wearing a dark tracksuit with a yellow logo.
Det Con Tracy Maclean, of Surrey Police, urged people not to walk home alone following a night out.
She said: "Think of alternatives to walking home, would ordering a licensed taxi be a better option?
"Or could someone you know and has not been drinking alcohol give you a lift or pick you up?"
