GitLab has remediated an issue in GitLab CE/EE affecting all versions from 13.11 before 19.2.8, 19.3 before 19.3.5, and 19.4 before 19.4.2 that, under certain conditions, could have allowed an authenticated user controlling a Kubernetes agent to cause sensitive authentication tokens to be sent to an unintended server due to improper redirect validation in the Kubernetes proxy.
Upgrade to versions 19.2.8, 19.3.5, 19.4.2 or above.