For software security testing, I have a list of sources I am going through on a weekly basis. It includes some of the newsletters, product updates and new vulnerabilities one should look for. For the software testing in general, I am mainly getting the updates from the videos on platforms such as YouTube. 

I read a lot of artiles on the topic and also follow a few testers on linkedin and Youtube. Also a good community like ShiftSync helps see what are the current concerns and topics for the futurure of IT and Software testing