All versions of Argo CD starting with v0.11.0 are vulnerable to a variety of attacks when an SSO login is initiated from the Argo CD CLI or the UI. The vulnerabilities are due to the use of insufficiently random values in parameters in Oauth2/OIDC login flows. In each case, using a relatively-predictable (time-based) seed in a non-cryptographically-secure pseudo-random number generator made the parameter less random than required by the relevant spec or by general best practices. In some cases, using too short a value made the entropy even less sufficient. (The specific weak parameters are listed in the References section.)

The attacks on login flows which are meant to be mitigated by these parameters are difficult to accomplish but can have a high impact (potentially granting an attacker admin access to Argo CD). The CVSS for this Security Advisory assumes the worst-case scenario.