Social networks and blogs
Logging on to social networking sites and going through the blogs of other bug bounty hunters is one of the best ways to stay up-to-date with all the developments happening in the field of security.
Exploitware Labs
Exploitware Labs (https://www.facebook.com/ExWareLabs/) is a Facebook page that publishes daily information about new vulnerabilities, news, projects, and proofs of concept.
Philippe Hare Wood
Philippe Hare Wood (https://philippeharewood.com/) is a bug bounty hunter who has discovered vulnerabilities mainly on Facebook and Instagram. He also publishes the solutions to some CTFs.
PortSwigger's blog
PortSwigger (https://portswigger.net/blog), the company that developed Burp Suite, has its own blog, where people post information about extensions, analyse with Burp Suite, and development around Burp Suite.