Vulnerability · Published Sep 21, 2026 · Assigned by GitHub_M

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

High 7.4

In plain English

A high-severity authentication bypass by spoofing in joplin from laurent22. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities).

Severity (CVSS 3.1)7.4High

Exploit odds (30 days)0.5%top 58.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 (as reported)

Vendor	Product	Versions
laurent22	joplin	< 3.7.2

Weakness: CWE-290 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

References

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