CVE-2017-18909

CVE-2017-18909 describes a vulnerability in Mattermost Server versions prior to 3.9.0, where the SAML implementation does not enforce mandatory encryption and signature verification. This oversight allows an unauthenticated attacker to potentially compromise the confidentiality of sensitive information. With a CVSS score of 7.5 (High), the vulnerability is easily exploitable over the network with low attack complexity, leading to high confidentiality impact. There is no evidence of active exploitation, public exploit code, or inclusion in the KEV catalog, though it has received some community discussion and media coverage.