Irish scum-half Stringer, who arrived on loan from Munster earlier in the week, had spent 38 minutes watching Exeter dominate much of the first half of this LV=Cup clash while Bath looked anything but the home team.
However, the 35-year-old crossed twice in the second half to earn Bath the victory. It was Exeter's first defeat in this season's competition and they still have not beaten their west country rivals in a competitive match since 1978.
Tom Heathcote contributed six points for Bath, while Henry Slade kicked two first-half penalties for the visitors.
Harlequins went to the top of Pool One of the LV= Cup with a flattering 23-6 victory over a battling London Welsh side in a scrappy match at the Stoop.
The Quins now face Ospreys at Bridgend next Sunday in their final group fixture when a draw would be sufficient to see them through to the semi-finals. For Welsh it was their third consecutive defeat in the tournament.
Mark Lambert and Dave Ward crossed for Quins, with Ben Botica contributing 13 points, while Alex Davies kicked two penalties for Welsh.
Northampton ended a three-game Franklin's Gardens try-drought to maintain top spot in Pool Four of the LV= Cup with a 26-7 victory over Gloucester.
Saints had not scored a try in front of their own fans since November 24 but Luther Burrell and Alex Waller touched down to end that barren spell, with Ryan Lamb and Stephen Myler kicking the rest of their points.
Ryan Mills scored Gloucester's only try of the game in the first half before adding the extras.
Danny Cipriani claimed a 21-point haul as relegation-threatened Sale put their dismal league campaign behind them with victory over a severely understrength Scarlets in the LV= Cup.
The fly-half scored a second-half try and kicked 16 points as Steve Diamond's men kept alive their hopes of reaching the knockout stages of the Anglo-Welsh tournament.
Sale have endured a bitterly disappointing Aviva Premiership campaign and lie bottom of the table after 13 games.
But they ultimately had too much power for their Welsh visitors as tries from Richie Vernon, Charlie Amesbury, Cipriani and replacement Charlie Ingall secured the win.
Holders Leicester kept their LV= Cup hopes alive with a five-try 34-8 victory over great rivals Wasps at Welford Road.
The win puts Leicester, who started the day second bottom of Pool Two, on nine points and still in the hunt with just one match left.
They go away to Scarlets next week, aiming to top the group and reach the semi-finals.
Leicester's tries came through Logovi'i Mulipola, Michael Noone, Mathew Tait and Vereniki Goneva, who crossed twice, with Dan Bowden kicking a conversion and a penalty and Matt Cornwell two conversions.
Wasps, who have not won at Leicester since 2008, were outplayed for most of the game and scored a consolation try through replacement Hugo Southwell near the end to add to a penalty from Tommy Bell.
Fly-half Steffan Jones landed six penalties for Newport Gwent Dragons as the Ospreys saw their chances of reaching the latter stages of the LV= Cup take a big knock with an 18-14 defeat at a drenched Rodney Parade.
Man of the match Jones booted the Dragons to their first win in the competition this season although the feisty match only came to life in the final quarter after Ospreys flanker Jonathan Thomas scored the only try of the evening.
Matthew Morgan kicked three penalties for the visitors but they were not helped by having to play 20 minutes of the match with 14 men through two sin-bins against one for the Dragons.
The defeat leaves the Ospreys third in Pool Four with five points from their three matches, while Newport remain bottom of Pool One with four points.
The match was held up for six minutes early on after a serious ankle injury to home wing Michael Poole.