The noun frontstabbing denotes the action or practice of attacking, or acting against, someone in a candid or open manner, as opposed to deceptively or duplicitously. (However,  frontstabbing has occasionally been used literally in reference to physically attacking someone—cf., for example, quotation 2 below.)

This noun was coined after backstabbing, which denotes the action or practice of attacking, or acting against, someone in a treacherous or underhand manner.

The noun frontstabbing occurs, for example, in a review of Vice (2018), a U.S. film written, produced and directed by Adam McKay, starring Christian Bale as the former U.S. Vice President Dick Cheney—review by Richard Roeper, published in The Times-Tribune (Scranton, Pennsylvania, USA) of Wednesday 16^th January 2019 [page G8, column 1]:

In Adam McKay’s free-ranging, tone-shifting, darkly funny, super-meta, hit-and-miss, absurdist biopic “Vice,” Bale nails it as the resilient, backstabbing, front-stabbing, ruthlessly ambitious Cheney.

The earliest occurrences of the noun frontstabbing that I have found are as follows, in chronological order:

1-: From the account of a meeting of Kells Urban Council, published in The Drogheda Independent (Drogheda, Louth, Ireland) of Saturday 9^th May 1914 [page 3, column 5]—the chairman was Mr Gartland, Justice of the Peace:

At this point the clerk whispered something to the chairman, and Mr Smith remarked—What are you hinting to the chairman? Clerk—He will tell you himself? Mr Tully—That hinting is no good. Clerk—No, not a bit. Mr Tully—We will have no back or front stabbing here. It will all appear on the front pages.

2-: From Passing the buck, by the U.S. newspaper columnist, radio and television critic, novelist, and television host John Crosby (1912-1991), published in The Observer (London, England) of Sunday 18^th February 1973 [page 11, column 5]:

There is nothing that puts the roses in the cheeks of the diplomats like a conference, and there are a great many going on around the world right now. I talked to a diplomat fresh from Helsinki, where the European Security Conference (or ESC) adjourned the other day. He told me that conferences are what a career diplomat yearns for these days. In the old days he wanted to be Under-Secretary or perhaps Ambassador. Now he just wants a nice conference in some nice European backwater like Helsinki, or Brussels or Geneva—far from the back-stabbing of the State Department or the front-stabbing of the Washington streets, which are highly unsafe to walk.

3-: From a review of The Holcroft Covenant (1978), by the U.S. novelist Robert Ludlum (1927-2001)—review by Betty Ligon, published in the El Paso Herald-Post (El Paso, Texas, USA) of Saturday 27^th May 1978 [page 4, column 6]:

We find Noel Holcroft, who is instructed in a passionate letter from his father (one of the biggest of the big Nazi big-wigs) to find the eldest offspring of two other Nazi big-wigs and start tapping a $780 million dollar Swiss account in order to “make amends” for the Holocaust.
Now that’s the start of the book. What happens from there seems to be somewhat at a Ludlum trademark—crosses, double-crosses, back-stabbing, front-stabbing, front and back shooting, and the multiple use of a piano wire snapped around the neck.

4-: From The Morris File, by the Scottish newspaper columnist Albert Morris (1927-2018), published in The Scotsman (Edinburgh, Midlothian, Scotland) of Thursday 4^th June 1981 [page 10, columns 2 & 3]:

When these fragments of nicotinal [sic] bliss were not available I would go hazard in black Turkish or Greek fags—the cigarette equivalent of rump steaks fried with gun-powder—that had all the whiff of an Albanian bazaar on a hot day and hinted at Balkan intrigue, sultry nights in foetid alleyways, heavily-shutterd [sic] seraglios and front-stabbing and back-scratching and would make non-smokers turn pale and rush to open wide the nearest windows.

5-: From a review of the U.S. television miniseries Princess Daisy (1983)—review by Diane Holloway, published in the section Show World [page 2, column 1] of the Austin American-Statesman (Austin, Texas, USA) of Sunday 6^th November 1983:

Running down the laundry list of ingredients, we find lust (lots of lust), romance (not the same thing as lust), sex (not the same thing as lust or romance), virginity, frigidity, incest, backstabbing, frontstabbing, revenge, intrigue, greed, royalty, poverty.

A back-formation from the noun frontstabbing, the verb frontstab (someone) means: to attack, or act against, (someone) in a candid or open manner, as opposed to deceptively or duplicitously.

The earliest occurrence of the verb frontstab that I have found is from Watching Brief, published in Scotland on Sunday (Edinburgh, Midlothian, Scotland) of Sunday 28^th July 1991 [page 29, column 5]:

REDUNDANCY is for some a traumatic experience, but for others it is an art to accomplish and perfect: the art of firing. Since this simple truth was grasped, the industry of outplacement counselling has fluorished [sic] in Canada over the past 15 years, and with the lingering recession it threatens to become one of the most profitable fields.
Four organisations dominate the ‘firing business’, providing help for the newly fired employee in recovering confidence and self-esteem and brushing up interview and letter-writing skills. They also offer advice to nervous employers on how, when and where to best front-stab old friends and good colleagues.