Donald Trump Jr., pictured in December 2016. (Eduardo Munoz Alvarez/AFP/Getty Images)

A one-digit mistake by CNN on Friday armed President Trump with new ammunition for another fusillade against the media. Hours later, the president fired away at a rally in Pensacola, Fla.

“CNN apologized just a little while ago,” Trump gloated. “They apologized. Oh, thank you, CNN. Thank you so much. You should’ve been apologizing for the last two years.”

CNN reported Friday morning that Donald Trump Jr. received an email on Sept. 4, 2016, that granted special access to WikiLeaks documents. The network said in an online article that the email had been “described to CNN by multiple sources.”

But The Washington Post obtained the email itself and reported Friday afternoon that the message was actually dated Sept. 14, 2016 — a difference that sets Trump Jr.’s receipt 10 days later.

The date matters. CNN’s report indicated that the Trump campaign had been fed hacked email files belonging to the Democratic National Committee and former secretary of state Colin Powell more than a week before the files were released publicly.

“Interestingly,” CNN reporter Manu Raju said on the air, “the same day that Donald Trump Jr. received this email was the first time that he appears to have tweeted about WikiLeaks.”

CNN presented the timing of Trump Jr.’s tweet as a possible reason to doubt his claim that he never even saw the email.

The later email date reported by The Post means that Trump Jr.’s first tweet about WikiLeaks could not have been prompted by the email, since the president’s eldest son did not receive the message until 10 days after tweeting.

More important, the later date means that the email did not provide the Trump campaign with early access to WikiLeaks documents after all. The DNC files shared with Trump Jr. via a link and a “decryption key” on Sept. 14, 2016, had been posted online and advertised on Twitter by WikiLeaks the day before. And the Powell files had been posted online hours before Trump Jr. received the email from a person who identified himself as Michael J. Erickson.

As The Post’s Rosalind S. Helderman and Tom Hamburger noted in their report on the correct date of the email, “the writer may have simply been flagging information that was already widely available.”

CNN issued a correction and a statement on Friday afternoon.

CNN’s report, though flawed, adds to previous reporting by the Atlantic that WikiLeaks called Trump Jr.’s attention to some of its disclosures through private Twitter exchanges and offered advice during and after the campaign. For example, WikiLeaks tipped off Trump Jr. to the launch of a political-action website opposing his father and provided a link, which Trump Jr. tweeted, that highlighted “many great stories the press are missing” in the hacked emails of Hillary Clinton campaign chairman John Podesta.

The wrong date in CNN’s report exaggerated the apparent coziness between the president’s team and WikiLeaks, however.

You could practically hear the cry of “fake news” building in President Trump’s lungs before he took the stage in Pensacola and let it rip.

The “fake news” label suggests intentional deception, but there is no evidence that this was anything but a mistake. Plus, The Post’s report on the true date of the email is an example of how the press often polices itself — contrary to conspiratorial notions of a “corrupt cabal,” as Sean Hannity calls the media.

Still, a week after ABC made an even bigger error that also involved the inaccurate reporting of an event’s timing, CNN’s slip-up played into Trump’s effort to cast the media as unreliable and out to get him.

“Did you see all the corrections the media's been making?” Trump said Friday night. “They've been apologizing left and right. They took this fraudster from ABC — they suspended him for a month. They should have fired him for what he wrote.”

This post has been updated to include a statement from CNN and Trump's remarks in Pensacola.