The news seemed to bode well for Kushner, whose business dealings and past omissions to the government about his foreign contacts had been viewed by some as the reasons for his lengthy background review process.
But former federal prosecutor Renato Mariotti says he wouldn't go that far.
"It's safe to say this clearance would not have been granted if his name wasn't Jared Kushner," Mariotti said in an interview, referring to Kushner's relationship to the president. (Mariotti is a Democrat who is running for Illinois state attorney general.)
Kushner's family business debts have raised concerns that he is vulnerable to influence or manipulation in his role with the Trump administration. Kushner Companies' pursuit of business in China, for instance, has been viewed as a conflict of interest.
He also had to repeatedly update a security clearance form to include more than 100 contacts that were initially omitted — including some with foreign sources.
The form had been updated to include a meeting he attended with Kremlin-connected Russian lawyer Natalia Veselnitskaya in a June 2016 meeting at Trump Tower, alongside Donald Trump Jr. and former campaign chief Paul Manafort.
The meeting was pitched to Trump Jr. as an opportunity to learn compromising information about Trump's political opponent, Hillary Clinton.
Mariotti said it's possible that the officials conducting the background check decided to grant his permanent security clearance because they believed the risk that his access could pose to the United States "was manageable, or not significant enough to deny him clearance."
But passing the background check doesn't necessarily clear him of any wrongdoing, Mariotti added. "I would tell him he should not assume that means he's out of the woods with Mueller."
Lowell did not immediately respond to CNBC's request for comment.
Despite being a leading player in the Middle East peace process and U.S. relations with China, among other roles, Kushner maintained an interim security clearance that allowed him to access only high-level information.
His ability to view top secrets was reportedly downgraded in February by chief of staff John Kelly, who diminished the access of White House officials with interim clearances after former aide Rob Porter was accused of domestic abuse by two former wives.
Kushner's security clearance does suggest that, at the very least, the FBI does not consider him to be a foreign agent or untrustworthy with government secrets, said Steven Mulroy, a professor teaching constitutional law at the University of Memphis.
But Kushner could still face potential legal troubles over, for example, his initial failures to disclose contacts on his security form, Mulroy said. Although it may not pose an ongoing security threat, Mulroy said the question remains open whether Kushner broke the law with his omissions.
Mulroy also raised the possibility that Kushner's second meeting with the special counsel may have helped propel his background check to completion.
"It's possible that if Mueller thought Kushner was being cooperative and forthcoming, that might have allowed them to make a recommendation," Mulroy said.
Still, Mulroy said, "It doesn't mean he's completely in the clear."