I haven't got much sources for you but what I've picked up over the years: a lot of OpenBSD's security is just old fashioned manual code review and audits, and there are not enough eyeballs. Someone like Ilja van Sprundel can go in the source code and find a bunch of issues without too much trouble [1]. I don't see any concentrated efforts to improve the status quo (where's formal methods, where's automated fuzzing, where are initiatives to employ more safe programming languages, static analysis, etc.). And while OpenBSD pride themselves on their mitigations, they aren't exactly state of the art and some of the more recent stuff (like trying to eliminate ROP gadgets) seems just futile. The biggest thing OpenBSD did with mitigations was enabling them by default for the base system and ports. What does anyone remember OpenBSD for in 2010-2020? Pledge, probably. That's a nice thing but more for containing the damage than actually making stuff secure in the first place.

https://www.csoonline.com/article/3250653/is-the-bsd-os-dyin...

My concern (and the concern of many others, I think) is that if OpenBSD suddenly got enough attention from the wider security community, including people who actively look for holes that can be exploited, there'd be plenty of important stuff found. Until then, these issues sit quietly waiting for a malicious party to discover them. There's quite some fanfare for OpenBSD, but how many of you are actively auditing the code? I'm subscribed to cvs@ and tech@ and I read them daily and I just don't see much contribution at all from outsiders. And when I do see it, it's mostly stuff like fixing typos or amending man pages. All the commits that change code with security implications tend to come from the core developers, and are reviewed by a handful of people at best. And I have seen some obviously broken stuff slip through.