Apache Guacamole 1.2.0 and 1.3.0 do not properly validate responses received from a SAML identity provider. If SAML support is enabled, this may allow a malicious user to assume the identity of another Guacamole user.
https://lists.apache.org/thread/4dt9h5mo4o9rxlgxm3rp8wfqdtdjn2z9