Liam Newby was attacked as he walked up Town End Farm in Sunderland.
Liam aged 27 was stopped by three lads as he walked up the hill and was asked for a light.
When Liam looked down his face was slashed while he was out walking his friends dog at 2pm on Saturday afternoon.
Northumbria Police released a statement saying “The victim sustained a serious facial injury and was able to call for an ambulance. Emergency services attended and the man was taken to hospital for treatment.
“A photograph of the victim’s injuries has been released to show the extent of the incident.
“Police inquiries into the incident are continuing and extra patrols are in the area to carry out inquiries and reassure any concerned members of the public.
“Any witnesses, or anyone with any information about the incident, should call police on 101 quoting reference 598 020416 or Crimestoppers anonymously on 0800 555 111.”