Advertisers on Facebook are able to completely rewrite the displayed headline for news stories, CBC News has learned, opening the door for potential disinformation to spread on the platform while using news media branding as cover.

When placing an ad on the platform, one option is to include a link to a website, including links to news stories. The news story's real headline is auto-filled into the ad copy, but advertisers have the option to rewrite the headline. However, the article's website address still appears in the ad, giving the impression that the headline is the one written by the article's author.

This policy raises the possibility that it could be abused by political parties or third-party advertisers during the federal election campaign.

"This is essentially, it would be a situation where Facebook is hosting and allowing and accepting monies for a misleading, essentially, political ad or a political weapon, at that point," said Jennifer Grygiel, an associate professor of communications at Syracuse University.

"Any time that you can present a story as being different than it is, there's an opportunity for it to be abused," said Aleksander Essex, a professor of computer science at Western University in London, Ont. "What you see and what's displayed to you online can potentially be changed in a number of ways. In this case, it sounds like Facebook is explicitly allowing it out of carelessness."

Facebook is aware of the issue and said it is planning changes.

"We have a system that gives publishers control over how their links appear on Facebook. We're working to put additional safeguards in place by the end of this year to make sure advertisers don't misuse this tool," said a Facebook spokesperson in an email to CBC News.

Before 2017, Facebook users and page administrators could change headlines of the articles they shared on the platform, allowing them to dramatically alter the way the articles were presented.

This function was abused by people looking to sow confusion and misinformation . One CBC article with a fake headline that included vulgar language circulated widely in 2015. Because the link included a CBC URL, many users believed the headline was real. A social media editor wrote a piece to clarify the headline was false.

Facebook removed the ability to alter headlines in June of 2017 as part of its efforts to limit the spread of disinformation. But there is one exception to this rule: pages which purchase ads can still modify an article's headline, as long as it's part of an advertising campaign.

In fact, this very tactic was recently used in the UK . That country's Conservative Party ran an ad in the first week of September containing a BBC article whose headline was, "£14 billion pound cash boost for schools".

On the left is an ad run by the Conservative party in the U.K. with the headline changed. On the right is the BBC article with the headline as it originally appeared. The actual text of the article contradicts the headline in the ad. “Describing this as a £14bn increase would make the government seem more generous than it is in fact being”, wrote BBC head of statistics Robert Cuffe in the article. (Screengrabs/Facebook/BBC)

There was one problem: the article's title had been modified by the party.

The actual BBC story is headlined "School spending: Multi-billion pound cash boost announced," and instead put the number at £7.1 billion, criticizing the government's use of £14 billion pound figure as not the usual way of calculating spending.

"Describing this as a £14bn increase would make the government seem more generous than it is in fact being", wrote BBC head of statistics Robert Cuffe in the article.

In all, the UK's Conservative Party ran five different version s of this misleading ad, reaching a potential audience of 222,000 to 510,000 Britons. The ad is no longer active, and when searching for it in the Facebook Ad Library, users get a message that the ad did not conform to Facebook advertising standards and has been taken down. It's still possible to view the original ad.

Since then, the Conservative Party told the BBC: "It was not our intention to misrepresent by using this headline copy with the news link, where the BBC's £7bn figure is clearly displayed, but we are reviewing how our advert headlines match accompanying links."

According to Grygiel, this shows a failure of Facebook's ad service.

"They should be building product in a way that is not democracy damaging," they said.

Grygiel said it is Facebook's responsibility to create advertising infrastructure that wouldn't allow advertisers to change headlines on articles. They pointed out that Facebook has a higher standard of what it will allow for advertising, because people can't opt out of it.

"Because, again, these are people who are being targeted and this content is being forced on a viewer, as an ad, and so it has a higher threshold of accountability. So, they need to do better," they said.