What’s Vulnerable › Vulnerabilities

CVE-2026-55210: Joplin: SAML SSO account takeover via email-based account linking (missing is_external check in ssoLogin)

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-21 · updated 2026-09-23
• Weakness: CWE-290

Description

Joplin is an open source note-taking and to-do application that organises notes and lists into notebooks. Prior to 3.7.2, Joplin Server's UserModel.ssoLogin() returns an existing account matched by an IdP-asserted email without checking the account's is_external flag. In deployments using mixed local and SAML authentication, an attacker whose IdP session can assert a local user's email can pass POST /api/saml, receive a session for that local account, and access or modify the victim's notes, files, and settings without knowing the local password. This issue is fixed in version 3.7.2.

Affected products

• laurent22 joplin: before 3.7.2

References

• https://github.com/laurent22/joplin/commit/b6d69d072919cbe769234f93d95ed21e1ec129b2
• https://github.com/laurent22/joplin/pull/15647
• https://github.com/laurent22/joplin/security/advisories/GHSA-5px3-4f5x-hjc5

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