A logic issue was addressed with improved state management. This issue is fixed in macOS Mojave 10.14.5, Security Update 2019-003 High Sierra, Security Update 2019-003 Sierra, iOS 12.3, tvOS 12.3. Users removed from an iMessage conversation may still be able to alter state.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-8631
Reference (s):
- https://support.apple.com/en-us/HT210118
- URL: https://support.apple.com/en-us/HT210118
- https://support.apple.com/en-us/HT210119
- URL: https://support.apple.com/en-us/HT210119
- https://support.apple.com/en-us/HT210120