The incident happened yesterday (22/2) at about 2.05pm in Trenchard Street, Fairford Leys.
The victim, a 26-year-old woman, was walking in Trenchard Street towards the Honeybee pub when she was approached by two men.
One of the men barged into her, causing her to be pushed against the wall.
As she regained her balance, the second man touched her inappropriately. The victim then managed to get away from the two offenders.
The first man is white, aged between 40 and 50, with an average build and about 5ft 6ins tall.
He had short greying hair which was slightly receding and was wearing loose fitting dark blue jeans and a dark puffer jacket.
The second man is white, aged between 30 and 40, with a skinny build and about 5ft 6ins tall.
He had short, dark, unkempt hair and was wearing a dark puffer jacket.
Both of the men may have had eastern European accents.
Investigating officer, PC Hannah Phillips, based at Aylesbury police station, said: “This was a very frightening incident for the victim, who was subjected to a sexual assault.
“I am appealing for anyone who may have witnessed this incident, or who has any information which they think could help our investigation, please call the Thames Valley Police non-emergency number 101.”
If you do not want to speak directly to the police you can contact the independent charity Crimestoppers anonymously on 0800 555 111. No personal details are taken, information is not traced or recorded and you will not go to court.