Since CISA killed it's RSS feed[1], If anyone is interested, I created an account here that will allow anyone to subscribe both via the fediverse and via RSS using the mastodon RSS feed for that account. The account is @CISA Email Reflector 1.

Cybersecurity and Infrastructure Security Agency CISA

Update to How CISA Shares Cyber-Related Alerts and Notifications | CISA

CISA is changing how we announce cybersecurity updates and the release of new guidance.