Microsoft suggests registry hack for smart card users
Windows requires RSA smart‑card certificates to use KSP not CSP; a registry workaround (DisableCapiOverrideForRSA=0) works until April 2026 and apps must migrate.
Security patch or self-inflicted DDoS? Microsoft update knocks out key enterprise functions
KB5066835's shift from CSP to KSP caused widespread Windows failures affecting smartcard authentication, IIS, WinRE input devices, and updates across multiple Windows and Server versions.