Benjamin Griveaux, who served in Macron's cabinets and ran as the presidential party candidate in Paris for the mayor office (currently held by Socialists), rescinded his candidature after a masturbation video surfaced some days ago. The details are a bit murky, we don't know it's his dick (the media has decided on using "video of a sexual nature" without more details) but just leaving the race without a fight would suggest it is, that's something he sent to a woman he was consensually exchanging with reportedly (he's married), apparently it was leaked by a Russian "artist and activist" (he was arrested today for an alleged fight in a bar, he also tried to torch the facade of a bank to make a point some time ago) because he loathed the hypocrisy of the candidate. AFAIK it's not clear how he got ahold of the video.
Macron's party already had to contend with a dissident candidate (eccentric mathematician Villani) and polling indicates Griveaux was trailing behind incumbent Anne Hidalgo and the right-wing candidate Rachida Dati before the whole hubbub.
Punditry and media seem to fall squarely on the "unbecoming in a democracy, breach of privacy, mobs 2.0 are frightening" side of the argument.