Is there an actual problem that you discovered
The first step in determining of whether to disclose or not to disclose is if you found something that has an impact. Would the information you found have an impact on your current employer (tech company) if the media came to the same conclusion as you and decided to broadcast it to the world? If not then there is no point in reading any further you have no obligations in anyway. Let it go and look forward to your new job.
Types of obligations
Per the wording of your question you do not have a moral or ethical obligation to let your current employer know, even if it has the potential to hurt the company. If you signed any document like what people sign when they get a government clearance then you would be legally obligated to report this information (this likely does not apply to you, but you should know what you signed when you started working for them). If your job description included things like security, public relations, or interacting with the security company in question, then you would be obligated to act upon it since that would be part of your job (again I am assuming this does not apply to you).
I could only think of one reason to share it with your current employer despite not being obligated to which is: You don't want to risk your current company getting damaged. If your company gets damaged it can mean downsizing which could mean loss of employment or the work place becoming toxic.
Sharing can be dangerous
Lastly note that if you do share this with your current employer there is a slim chance that this can go far differently then you would expect. For example it could turn out that it was your company that produced the document and the security company has no responsibility or knowledge of this. As a result they (tech company) could try to react by suppressing all information on it and, discrediting those who know of it or, and/or retaliating against the person who exposed it (which in this case would be you).