Warriors stormed to a 19-0 lead with tries from Peter Horne, Josh Strauss and Jonny Gray, but the Leinster staged a late revival.
Jack McGrath and Tom Denton found their way over the whitewash to put the Irish province into the lead for the first time, but ill-discipline in the dying minutes led to Hogg's successful penalty.
The Ospreys are the early-season pace-setters at the top of the GUINNESS PRO12 table, beating Benetton Treviso 44-13 in a six-try performance.
Dan Biggar added 17 points from the tee, converting four of the six tries and adding three penalties for good measure.
Fellow Welsh region Cardiff Blues also picked up a winning bonus point at Zebre with 21-year-old fly-half Rhys Patchell scoring a try and kicking 16 points.
Wales international Alex Cuthbert was one of the other four try-scorers in Parma, as the Blues avenged their two defeats to Zebre last season.
The Scarlets were left to pick their wounds after letting Ulster come from 14-points down to snatch a 32-32 draw at Parc y Scarlets.
Ireland wing Andrew Trimble ran over for the last-gasp try, working his way under the posts and allowing Ian Humphreys to kick the equalising conversion.
On Friday, Munster lost their third home game on the trot, falling 14-13 to Edinburgh Rugby at Thomond Park despite two tries from CJ Stander.
New Edinburgh kicker Tom Heathcote scored nine points from the tee, with fellow former-Bath Rugby back Jack Cuthbert scoring the Scottish side's only try.
And Pat Lam's Connacht started their season with a bang, downing Newport Gwent Dragons 16-11 thanks to an inspired performance from Jack Carty.
Eoin McKeon and Danie Poolman scored the tries for Connacht, Poolman's the result of a lovely kick by Carty, while Nic Cudd touched down for the Dragons.
TRY OF THE WEEKEND
The best tries are those which come from innocuous beginnings, like Peter Horne's opener for Glasgow at Scotstoun. Alex Dunbar spotted a gap in the Leinster defence, passing wide to Tommy Seymour - via Henry Pyrgos - who flicked the ball inside to Horne while being bundled out of bounds.
Horne then brushed aside one would-be Leinster tackler to dot down in the 17th minute.
BREAK OF THE WEEKEND
Blues full-back Dan Fish slipped through the Zebre defence like an eel to dot down Cardiff's third try in Parma. First sidling past winger Leonardo Sarto and evading full-back Hennie Daniller's attempted tackle to touch down near the posts.
PLAY OF THE WEEKEND
Connacht fly-half Jack Carty could have been forgiven for playing conservatively, having been taken out in the air by Dragons skipper Lee Byrne. But with Byrne joined by Tyler Morgan in the sin bin Carty produced a pinpoint crossfield kick to winger Danie Poolman, who touched down in the corner.
PLAYER OF THE WEEKEND
Cardiff fly-half Patchell laid down his statement of intent ahead of the arrival of Gareth Anscombe at Arms Park next month, scoring 21 points, including the first try of the game. Not a bad performance in 33 degree heat.
The highlight of his 16 points from the tee was undoubtedly when he showed off the power in his right leg, nailing a penalty from well inside his own half.
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