CVE-2023-38686 (sydent)

Sydent is an identity server for the Matrix communications protocol. Prior to version 2.5.6, if configured to send emails using TLS, Sydent does not verify SMTP servers' certificates. This makes Sydent's emails vulnerable to interception via a man-in-the-middle (MITM) attack. Attackers with privileged access to the network can intercept room invitations and address confirmation emails. This is patched in Sydent 2.5.6. When patching, make sure that Sydent trusts the certificate of the server it is connecting to. This should happen …

access address attack attackers certificates communications cve emails identity intercept interception man-in-the-middle matrix mitm network privileged privileged access protocol send server servers smtp tls verify version vulnerable