All Kubuntu releases?

• Kubuntu 15.04: https://web.archive.org/web/20151110133002/http://cdimage.ubuntu.com/kubuntu/releases/vivid/release/

• Kubuntu 15.10: https://web.archive.org/web/20160517131813/http://cdimage.ubuntu.com/kubuntu/releases/15.10/release/

• Kubuntu 16.10: https://web.archive.org/web/20170606120152/http://cdimage.ubuntu.com/kubuntu/releases/16.10/release/

• Kubuntu 17.04: https://web.archive.org/web/20171222021400/http://cdimage.ubuntu.com/kubuntu/releases/17.04/release

• Kubuntu 17.10: https://web.archive.org/web/20180628191845/http://cdimage.ubuntu.com/kubuntu/releases/17.10.1/release/

• Kubuntu 18.10: https://web.archive.org/web/20190629160724/http://cdimage.ubuntu.com/kubuntu/releases/18.10/release/

• Kubuntu 19.04:

  • https://old-releases.ubuntu.com/releases/kubuntu/releases/19.04/release/
  • https://old-releases.ubuntu.com/releases/kubuntu/releases/disco/release/

A recent clean up was done and some flaws were discovered

Steve Langasek (vorlon) writes

... In the process, I also discovered that the point release process as documented on https://wiki.ubuntu.com/PointReleaseProcess with regards to archival of prior point release artifacts has not been followed for some time, and while not-current point release images for releases.ubuntu.com were properly being moved to old-releases, the stale point release images for flavors on cdimage.ubuntu.com were not being archived. Because this was never a documented policy change, I've followed through on the missing step and taken down these various stale point release images (most of which, it should be noted, have an apt that's vulnerable to a known MITM attack and should not be used under any conditions).

https://lists.ubuntu.com/archives/ubuntu-release/2020-October/005113.html