An anonymous reader writes from a report on Help Net Security: Mozilla has asked a Washington State District Court to compel FBI investigators to provide details about a vulnerability in the Tor Browser hack with them, before they share it with the defendant in a lawsuit, so that they could fix it before the knowledge becomes public. The lawsuit in question is against Jay Michaud, a Vancouver (Wa.) teacher that stands accused of accessing and downloading child pornography from a website on the Dark Web. The FBI used a "network investigative technique" (NIT) to discover the IP address and identity of the defendant, which was only possible from a vulnerability in the Tor Browser. Why does Mozilla care to learn about the vulnerability? "The Tor Browser is partially based on our Firefox browser code. Some have speculated, including members of the defense team, that the vulnerability might exist in the portion of the Firefox browser code relied on by the Tor Browser," Denelle Dixon-Thayer, Chief Legal and Business Officer at Mozilla Corporation, explained.