Chesham came from behind to take three points off Salisbury, but lost both managers to late red cards.
The Whites were previously unbeaten at the Ray Mac since late November, but after going a goal up, the Generals were able to pull two back through Yearn and Weiss.
The hosts dominated the opening half with attempts on goal, yet the Whites struggled to make the Chesham goalkeeper sweat.
Salisbury's top-goalscorer, Noah Coppin, looked to change that after some hustle to regain possession led to a trip in the box from the opposition.
Coppin then netted the penalty with ease into the bottom-left corner to score his ninth goal of the season.
A comfortable half for the home side quickly turned on its head, as the visitors pulled one back in stoppage time of the opening half through midfielder Kai Yearn after a scramble in the Salisbury box.
The second-half became a bitty and tense affair as both teams looked to take the lead.
Substitute Hedges almost made an immediate impact with 20 minutes to go after a strike deflected to the feet of Coppin, whose effort was also blocked.
Chesham eventually took the lead via Weiss, who nicked the ball off Gbadebo and dinked the ball goal-bound in the 89th minute.
Late handbags in the dugout saw both Chesham managers see red in additional time that may have made some late for their Valentine's Day arrangements.