The issue was addressed with improved UI handling. This issue is fixed in iOS 12.4, watchOS 5.3. A user may inadvertently complete an in-app purchase while on the lock screen.
https://support.apple.com/HT210353
https://support.apple.com/HT210346
Source: Mitre, NVD
Published: 2019-12-18
Updated: 2019-12-20
Base Score: 2.1
Vector: CVSS2#AV:L/AC:L/Au:N/C:N/I:P/A:N
Severity: Low
Base Score: 2.4
Vector: CVSS:3.0/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N