7.4

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

Deferred
Published 21-09-2026Last modified 22-09-2026

Vulnerability summary

CVE-2026-55210 is a high (CVSS 7.4) Authentication Bypass by Spoofing vulnerability in laurent22 joplin. EPSS estimates a 0.48% chance of exploitation in the next 30 days, higher than 40.3% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.4/10
010
High · v3.1 (CVE.org)
EPSS score
0.48%
0%100%
Low · +0.10 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 21-09-2026
    PublishedVulnerability first disclosed.
  2. 22-09-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.48%

Chance of exploitation in the next 30 days

Percentile

40%

Versus all other CVEs

30-day change

Increase +0.10 pp

From 0.38% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Laurent221 product

1 vendor · 1 product

References

3 links