I just read the whitepaper (I am a long time Dashlane user) and they have a section on security of their javascript/browser extensions. They say that their extensions all use c++ so execute entirely outside of the javascript context. This would not have prevented the Lastpass exploit since all that was required as a malformed URL, but it is nice to see that Dashlane is thinking about this stuff. Also, had Lastpass not used js this exploit would've been harder to find (though not impossible).
Hello Julsimon, this is Simon from Dashlane's Support team. Thank you for your feedback. We have indeed ran multiple checks on our end and can confirm that we are not vulnerable to this type of issue. The code used for our auto-fill functions is shared on all our platforms and has been audited multiple times.