To quote the OpenID Shared Signals and Events working group page:

The Shared Signals and Events (SSE) Framework improves API efficiency and security by providing privacy-protected, secure webhooks. It is in use by some of the largest cloud services to communicate security alerts and status changes of users, continuously and securely to prevent and mitigate security breaches. It is currently leveraged by two applications – the Continuous Access Evaluation Protocol (CAEP) and Risk Incident Sharing and Coordination (RISC) to achieve this result.

This recently gained some traction, with the OpenID RISC Profile Secification 1.0 being adopted as an OpenID implementer's draft: https://openid.net/2022/08/27/second-implementers-draft-of-risc-profile-approved/

This website from Cisco and the OpenID foundation does a great job at explaining what it is: https://sharedsignals.guide

Conceptually, it is a framework send security events between parties. There are currently two specs defining types of events:

• RISC (Risk Incident Sharing and Coordination), which includes events about the account security, like:
  • when an account is deactivated/re-activated
  • when an account was compromised
  • when an identifier changed or was recycled
  • when an account is being recovered
• CAEP (Continuous Access Evaluation Protocol), which includes events about the level of access of a session, like
  • when a session is revoked
  • when a claim changed
  • when the ACR level changed
  • when a credential changed

I think it would make sense for Keycloak to support at least some of those events, both as a transmitter (the party sending those events) and as a receiver (the party getting those events). Personally, I'm interested with Keycloak sending those events, but receiving them would help for example to use Google's Cross-Account Protection (which is their marketing name for RISC events)