The attack occurred in Langston Road, at the junction with Chigwell Lane (A1168) shortly after 7.25pm on Wednesday evening. Essex police said the stabbing followed “an altercation” between the man in a white van and a red Ford Fiesta.
In a statement, the force said: “We are appealing for witnesses or anyone with dash cam to come forward a man in a van was stabbed in Loughton.
“It happened in Langston Road, at the junction with Chigwell Lane (A1168) shortly after 7.25pm today and was reported to have followed an altercation between a white van and a red Ford Fiesta.
“Both vehicles left the scene but the injured man was later located in Church Hill and has been taken to hospital for treatment.
“He is described as being in a life-threatening condition.
“A man and a woman have since been arrested on suspicion of GBH and are currently in custody.
“The junction of Langston Road and Chigwell Lane is a busy one and we believe there will be people who saw what happened or have dash cam footage of it.”
A spokesman added: “If you have any information you can submit a report online at https://www.essex.police.uk or use the ‘Live Chat’ button to speak to an online operator between 7am-11pm. Please quote incident 1136 of August 4.”