Mozilla has asked a federal judge to order the U.S. government to disclose a vulnerability in its Firefox web browser that the company says the FBI took advantage of in order to investigate users of a child pornography website. Mozilla filed papers in federal court in Tacoma, Washington, on Wednesday seeking information on the vulnerability.

Denelle Dixon-Thayer, Mozilla's chief legal and business officer, said a judge had ordered the vulnerability disclosed to lawyers for a defendant caught in the probe, Jay Michaud, but not to any of entities that could fix it.

"We don't believe that this makes sense because it doesn't allow the vulnerability to be fixed before it is more widely disclosed," she wrote.

Mozilla said it had asked if the FBI submitted the browser flaw through the vulnerability review process but not received an answer.