as I mentioned in another sibling, its because it's a very common denominator in high value targets. I didn't know its legacy was from OpenBSD but I really doubt that that helps it much in this scenario, when I say LPE I'm not talking about user to root elevation, I'm talking parsed text/control sequences to arb code execution in the user context. These will slip past llm classifiers as safe and I'm fairly sure that they are extremely common in codebases like tmux, despite them having strong security posture its just a threat that was previously a bit outlandish and not accounted for.

persisted malicious code running in your tmux process that you don't know about is probably not where you want to be, for obvious reasons.