SAML Authentication Flaw in Joplin Server Affects User Account Security

CVE-2026-55210

What is CVE-2026-55210?

The Joplin Server's SAML authentication feature is vulnerable due to improper validation of user accounts. Specifically, before version 3.7.2, the UserModel.ssoLogin() method allowed attackers to gain unauthorized access to user accounts by exploiting an IdP-asserted email match. When mixed local and SAML authentication is used, an attacker could leverage their IdP session to impersonate a local user without needing their password, thereby accessing and potentially modifying sensitive information such as notes and settings. This vulnerability underscores the importance of robust account validation and is addressed in the latest release.

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