Apple seeded a supplemental update of macOS Catalina 10.15.7 on Thursday. The update looks to protect against some security vulnerabilities.
macOS Catalina Update Addresses Security Vulnerabilities
The Apple support document for the update lists three vulnerabilities that it has patched. There is one FontParser and two kernel vulnerabilities listed. The update is available on your computer via Systems Preferences. macOS Catalina 10.5.7 was only released a month against. The operating is expected to shortly be replaced by macOS 11 Big Sur in the very near future.