This issue was addressed with improved checks. This issue is fixed in iOS 13.3.1 and iPadOS 13.3.1. Users removed from an iMessage conversation may still be able to alter state.
https://support.apple.com/HT210918
Source: Mitre, NVD
Published: 2020-02-27
Updated: 2021-07-21
Base Score: 2.1
Vector: CVSS2#AV:L/AC:L/Au:N/C:N/I:P/A:N
Severity: Low
Base Score: 3.3
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N