> Allegedly WhatsApp uses Signal's encryption (OpenWhisper
About the partnership: https://signal.org/blog/whatsapp-complete/
But of course, in this case the issue seems to be either compromise of the device(s) via zero days, whatsapp usage simply being the target matrix - and/or a leveraging a zero day in whatsapp for full device compromise.
It's unlikely signal would be immune - they didn't Crack the encryption, they cracked the app/os.
In olden times the vector might have been a font, or a gif.
The only advantage signal has is a conservative interface and small userbase. I'm not sure if they do some kind of hard-line whitelisting of attachments though - if you can pack an exploit as a file, I'm pretty sure you could send it via signal.