Police said the victim was set upon by up to eight men in the Heights area at about 02:00 BST on Sunday.
A 30-year-old man was arrested but has since been released on police bail pending further enquiries.
Police have appealed for information about the attack.

The jazz film is the follow up to director Damien Chazelle's Academy Award-winning film Whiplash.
The People's Choice, voted for by the audience, has proved to be a decent predictor for Oscars success in recent years.
Previous winners include 12 Years a Slave and The King's Speech.
La La Land, set for release in December, stars Stone as an aspiring actress in Los Angeles who meets a jazz pianist (Gosling) who is trying to stay true to the music he has devoted himself to.
The film also stars singer John Legend and JK Simmons, who won an Oscar for best supporting actor for his performance in Whiplash.
La La Land has enjoyed rave reviews since premiering at the Venice Film Festival in August.
Chazelle wrote the script six years ago but was not able to persuade anyone to make it until he broke through with Whiplash in 2014.
Stone, who won the best actress prize at Venice for her La La Land role, previously starred with Gosling in Crazy, Stupid, Love.
Toronto's Platform prize for international directors was won by Pablo Larrain for Jackie, the Jacqueline Kennedy biopic starring Natalie Portman.
Raoul Peck won the People's Choice documentary award for I Am Not Your Negro, which follows the lives and assassinations of Martin Luther King Jr, Malcolm X and Medgar Evers.
The film is based on James Baldwin's unfinished book, Remember This House.
Follow us on Twitter @BBCNewsEnts, on Instagram, or if you have a story suggestion email entertainment.news@bbc.co.uk.

There have been ongoing industrial problems in the school for months.
The panel consists of leading educationalist Prof Sir Robert Salisbury, trade unionist John Corey and Belfast Metropolitan College's principal Marie-ThÃ©rÃ¨se McGivern.
Education Minister John O'Dowd has said he wants them to complete the investigation by early summer.
The secondary school, in the Andersonstown area of west Belfast, has 1,100 pupils.
About a third of its 70-strong teaching staff were absent for a period prior to Easter, and, in an unusual move last month, an associate principal was appointed to the school.
A group representing some parents also held a number of protests to express their concern about how the disputes were affecting their children.
Mr O'Dowd said that he wanted the panel to investigate events in the school, and make recommendations "to ensure the school's future".
"I consider the panel members to be eminently well qualified and experienced," he said.
"My priority continues to be to the pupils at the school and this investigation will give pupils, parents, staff and their representatives, and all those involved with the governance of the school, the opportunity to express their view."
The investigation will look at staff relationships, the role of senior leadership, governance of the school and the impact of the ongoing disputes on pupils.
Mr Corey was general secretary of Northern Ireland Public Service Alliance (NIPSA) union from 2003-10 and is currently a member of the Northern Ireland Human Rights Commission.
Prior to her role at Belfast Metropolitan College, Ms McGivern was director of development at Belfast City Council.
Sir Robert, meanwhile, recently chaired the literacy and numeracy task force in Northern Ireland and is a former professor of education at the University of Nottingham.
The National Association of Schoolmasters and Union of Women Teachers (NASUWT), which represents almost half the teachers at De La Salle College, welcomed the appointments.
It said the move "should reassure all partners in the De La Salle community that Minister O'Dowd is committed to finding a robust resolution to the recent period of challenge".
However, it said the terms of reference would be "critical to the success or otherwise of the investigation".
The NASUWT also said it will "seek assurances from the panel that their work will not cause any further disruption".
Jim Clarke, chief executive of the Council for Catholic Maintained Schools (CCMS), also welcomed the appointment of the panel.
"The background and experience of those who will be carrying out the investigation gives confidence to the process," he said.
"CCMS will continue with its ongoing work with the other interests through the agreed strategy. It remains focused on the needs and interests of the pupils at the school."
A 28-year-old man has been beaten by a gang armed with metal bars and bats in Coleraine, County Londonderry.
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Musical movie La La Land has picked up the prestigious People's Choice award at the Toronto International Film Festival (TIFF).
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A three-person panel has been appointed to carry out an investigation into De La Salle College in west Belfast.