Unvalidated gitlab URL parameter redirects OAuth authorize step to attacker-controlled host

draw.io is a configurable diagramming and whiteboarding application. Prior to version 29.7.9, the draw.io client accepts a ?gitlab= URL parameter that overrides the GitLab server URL used during OAuth sign-in. A crafted link causes the user's click on draw.io's "Authorize in GitLab" dialog to open a popup on the attacker-controlled host instead of gitlab.com. This can lead to credential fishing and session state token exfiltration. This issue has been patched in version 29.7.9.