Yahoo! (YHOO) shareholders may have felt a tinge of relief when AOL CEO Tim Armstrong told CNBC on Thursday that he was hopeful that parent company Verizon (VZ) - Get Report would close its planned purchase of the troubled Internet group's core assets, despite Yahoo's recently revealed massive cyber breaches.

But that assurance likely dipped when Verizon's digital chief, Marni Walden, told investors at a Citigroup conference in Las Vegas shortly after Armstrong spoke that "I can't sit here today and say with confidence one way or the other because we still don't know" whether the telecom will close the $4.8 billion purchase of Yahoo. Walden oversees Verizon's digital operations, Internet of things services and other emerging businesses. 

Yahoo! reiterated its faith that the transaction would proceed, however. "We are confident in Yahoo's value and we continue to work towards integration with Verizon," a Yahoo spokesperson said.

Since announcing the purchase of Yahoo's core business in July, Verizon has had to grapple with a pair of troubling cyber breaches at Yahoo.

First, Yahoo! revealed in September that 500 million customer accounts had been hacked in 2014.

If that weren't enough to spook the buyer, Yahoo said in December that another one billion accounts were hijacked in 2013.

Walden explained Thursday that "the strategic rationale" for buying Yahoo was to add to the scale of Verizon's AOL unit.

"Yahoo! has a very, very respected product organization, some capabilities that AOL doesn't have today," she said. "But it was really about taking an audience from hundreds of millions to into the billions."

In light of the attacks, Verizon has to make sure it is not "jumping off blindly off a cliff," she said.

"Has the asset changed in any way?" Walden asked with respect to Yahoo's core digital operations. "Are there other things that will need to happen to that asset?"

Verizon declined to comment beyond Walden's remarks.