Yahoo CEO Marissa Mayer AP/Lionel Cironneau Yahoo has for the first time formally raised the possibility of Verizon backing out of the $4.8 billion acquisition deal, because of the massive email hack the company announced in September.

In the "risk factors" portion of its latest quarterly filing disclosed on Wednesday, Yahoo listed a bunch of risks and uncertainties around the pending Verizon deal that could potentially make it fall through.

One of them said:

"...risks that Verizon may assert, or threaten to assert, rights or claims with respect to the Stock Purchase Agreement as a result of facts relating to the Security Incident and may seek to terminate the Stock Purchase Agreement or renegotiate the terms of the Sale transaction on that basis."

Risk factors are the worst-case scenarios companies are required to include in their quarterly and annual filings. So this doesn't necessarily mean Yahoo sees Verizon undermining the deal due to the security breach as an immediate risk. Still, it's interesting that Yahoo's mentioned this possibility for the first time in public.

Meanwhile, Yahoo reiterated that the security breach didn't have any "material adverse impact" on the company, although it hinted it could cost the company more in the near future, as it faces at least 23 lawsuits related to the data breach.

"We are confident in Yahoo’s value and we continue to work towards integration with Verizon," Yahoo's representative told us in a statement. Verizon declined to comment.

In September, Yahoo announced that at least 500 million user account credentials had been stolen from it in late 2014. Although Yahoo CEO Marissa Mayer reassured that the Verizon deal was still on track in its October earnings release, Verizon's lawyer Craig Silliman recently said the data breach could have "material" impact on the Verizon's purchase of Yahoo.