The problem is iOS AppStore.
If you update via the "Updates" tab, you don't get the latest version.
But if you search for WhatsApp as if installing it for the first time, then you get the new version.
The news outlets are all telling us to update, but until WhatsApp/Apple get their act together, there's no point. Worse still, people won't realise they need to do it again and will remain vulnerable indefinitely.
Updated WhatsApp on my iphone just now. The version I got was 2.19.50. According to the CVE it's still vulnerable. Unable to get 2.19.51 which is the first fixed version. Is this just me? Or is everyone else updating to a still-vulnerable version?