Fixed in v1.5.1, Argo version v1.5.0 was vulnerable to a user-enumeration vulnerability which allowed attackers to determine the usernames of valid (non-SSO) accounts because /api/v1/session returned 401 for an existing username and 404 otherwise.
github.com/argoproj/argo-cd/util/session github.com/argoproj/argo-cd/server/session
{ "nvd_published_at": "2020-04-08T18:15:00Z", "cwe_ids": [ "CWE-203" ], "severity": "MODERATE", "github_reviewed": true, "github_reviewed_at": "2021-05-25T18:19:26Z" }