I have searched in NVD and realized that patch release dates are not published with the specific vulnerability information of an application.
Other information like the "update date" do not necessarily map to the day a patch is released.
Can someone give me some direction on the appropriate place where I can easily get reliable information about the date of patch releases ?
After some research, I realised that the NVD does not publish all data about disclosed vulnerabilities since they opine that specific software vendors should have the most reliable information. Hence, patch release dates are available in the bug tracking repository of the vendors for example for OpenStack, such information is available in their Launchpad repositories.