The Upper East Side has been plunged into scandal after someone plastered the tony neighborhood with posters revealing an alleged affair between two members of staff at the ultra-ritzy Spence school.

When parents and nannies arrived for school drop-off at the exclusive all-girls school — whose aluma include Gwyneth Paltrow, Kerry Washington, Georgina Bloomberg and Anna Wintour’s daughter Bee Shaffer, to name a few — they were greeted with print-outs fluttering in the breeze that read “Attn Spence Families: [Redacted] is having an affair with [their] subordinate [,redacted,] who is married with a three year old son.”

The post listed the Spence job titles of both alleged parties to the illicit extra-curriculars.

One of the alleged lovers has been a trusted member of staff at the school for more than a decade. 

A source tells us that security tore down the signs, only to have them reappear by pick-up.

“Every group chat is blowing up,” said one source of parents who are shelling out over $70,000 a year in tuition. “People are literally losing their minds.”

We’re told the leading theory is that the married employee’s scorned wife is behind the vengeful fliers.

“The fact that the wife had the balls to go to Kinkos: Scorched earth policy,” says a source.

A rep for the school told us it will not be commenting.

The K-12 school is known as a feeder to the Ivy League.