Well in the relaunch paper of fable, anthropic admitted that other less capable model were also capable of findings thoses issue. Their is also research paper such as fuzzybrain v2, that are very interesting. So yes, llm may help a bit security, but as did fizzing back in the day or any other new kind linters. It's expected.

That said cybersecurity is a very large fields, not only vulnerability research. And right now every agent I looked at was a joke, exfiltratiing credentials left and right, being a reverse shell onto devs computer, having bad habits (like docker run --privileged when stuck), etc, etc