Twitter’s former head of security has blown the whistle on what he characterizes as sprawling cybersecurity weaknesses, including vulnerabilities that could lay the social media platform open to cyberattacks that could have major national-security implications.

That’s the allegation from Peiter “Mudge” Zatko, who sent a 200+-page disclosure to Congress detailing issues that he claims could allow foreign manipulation of users, account hacking and espionage, and disinformation campaigns ahead of the 2022 US midterm elections.

The disclosure, obtained exclusively by CNN and The Washington Post, most explosively alleges that the tech giant has one or more employees that are actually plants working for foreign intelligence, and that top execs have actively engaged in a cover-up of Twitter’s serious security holes.