Htmx has a bunch of logic that basically completely bypasses Content Security Policy stuff, as it has its own pseudo baked in "execute inline js" logic that executes arbitrary javascript via attributes on html elements.

Since this gets executed by the HTMX logic you load in from their library, it effectively allows an attacker to arbitrarily execute js via manipulating the DOM, and Content Security Policy won't pick it up because HTMX parses the attribute and executes on behalf of it (and you have already whitelisted HTMX in your CSP for it to function)

Result: It punctures a giant hole in your CSP, rendering it useless.

There's technically a flag you can flip to disable this functionality, but its via the dom so... not reliable imo. If I could pre-compile HTMX ahead of time with that functionality completely disabled to the degree it doesnt even get compiled into the output .js at all, then I would trust it.

But the fact all the logic is still technically there in the library I have loaded and I am purely relying on "this flag in the dom should block this from working, probably", I don't see that as very secure.

So until that gets fixed and I can compile htmx with webpack or vite in order to completely treeshake that functionality right the hell out of my output, I aint gonna recommend anyone use it if they want an iota of security on their site. It's got literally baked in security bypasses, don't use it.

Hell Id even just be happy if they released a "htmx-lite" package I could use, that just doesnt have that functionality baked in, thatd be enough to make me consider it.