Re: Packages providing Flatpak sandbox escapes via vulnerable MIME Type Handler

On 7/7/26 9:23 AM, Aaron Rainbolt wrote:
> This does not work. Someone did*exactly* this and I was able to
> leverage it to escape sandboxes (vuln report is under embargo at the
> moment). When you use a binfmt-misc handler, then when the sandboxed
> executable tries to run the program, the kernel runs it*in* the
> sandbox. When you use a MIME handler that gates access on the
> executable bit, where the handler executes outside of the sandbox,
> then when the sandboxed executable calls the MIME handler on a
> marked-executable file, the file runs outside of (and thus escapes)
> the sandbox.

Fedora double-dips. We register both as a binfmt-misc handler (only when you have 
wine-systemd installed) and via the upstream .desktop files.

I'm watching this thread but I don't have any suggestions at this time. My first 
impression is why does Flatpak change namespace/scope when performing MIME 
operations, but I don't know enough about the architecture to know why.

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