The New York Times’ Pulitzer Prize-nominated podcast about ISIS was an “institutional failure” that included shoddy reporting based off interviews with a “con artist,” executive editor Dean Baquet said Friday.

In a blistering editors’ note, the newspaper said the 2018 series “Caliphate” blew its journalistic standards.

An internal investigation into the 12-part series was launched after the main subject, Shehroze Chaudhry, was arrested in late September in Canada on charges he lied about his role in ISIS activity in Syria.

Chaudhry had told the Times that he participated in executions...