Investing.com - Equifax (NYSE:EFX) said Wednesday an unpatched web server vulnerability allowed a recent massive data breach.The breach compromised the personal details of as many as 143 million U.S. consumers.The breach exposed the information to hackers between mid-May and July, and sent shares in the credit reporting company tumbling.Equifax also indicated that it may still not know the full extent of the breach. The company said it has been "intensely investigating the scope" of the breach.Cyber security experts have said it was among the largest hacks ever recorded.