CVE-2026-55210

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.

Overview

State: PUBLISHED
Assigner (CNA): GitHub_M
CVSS severity: HIGH
CVSS score: 7.4 / 10
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Effective score: 7.4 / 10 HIGH source: CNA overview
CWE(s): CWE-290
Reserved: 2026-06-16
Published: 2026-09-21 21:14 UTC
Last updated: 2026-09-21 21:14 UTC
Source: https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/55xxx/CVE-2026-55210.json
Linked Threat: CVE-2026-55210 — Joplin: SAML SSO account takeover via email-based account linking (missing is_external check in ssoLogin)

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published: 2026-09-21 22:16:56 UTC
NVD last modified: 2026-09-21 22:16:56 UTC
NVD CVSS v3.1: 7.4 / 10 HIGH source: security-advisories@github.com
NVD CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Exploitability subscore: 2.2 / 10
Impact subscore: 5.2 / 10

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID: EUVD-2026-84176
Assigner: GitHub_M
Published: Sep 21, 2026, 9:14:31 PM
Updated: Sep 22, 2026, 1:07:10 PM
EUVD base score (CVSS 3.1): 7.4 / 10
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
EUVD-reported EPSS: 0.0000
Vendors: laurent22
Products: joplin (< 3.7.2)

ENISA 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.

EUVD references (3)

Affected products (1)

Vendor	Product	Versions	Platforms
laurent22	joplin	`< 3.7.2` (affected)	—

Vendor references (3)

References embedded in the original CVE record by the assigning CNA.

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

Web references (0)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

No web references attached yet.

NVD-tagged references (3)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

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

Remediations (10)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

Security Update Guide - Microsoft

web:msrc.microsoft.com

The Microsoft Security Response Center (MSRC) investigates all reports of security vulnerabilities affecting Microsoft products and services, and provides the information here as part of the ongoing effort to help you manage security risks and help keep your systems protected.

2026-09-22 16:48 UTC
Cisco Advance Notification for Publication of September 16, 2026 ...

web:sec.cloudapps.cisco.com

On September 16, 2026 , the Cisco Product Security Incident Response Team (PSIRT) published the advisories that are listed in the following tables. To remediate these vulnerabilities, Cisco strongly recommends that customers upgrade to the fixed software that is indicated in the advisories. For more information about changes in Cisco PSIRT vulnerability disclosure, see Strengthening the ...

2026-09-22 16:48 UTC
Microsoft Patch Tracker (September 2026): Exploit-Ranked | Senserva

web:senserva.com

Every Microsoft security patch (KB) and the CVEs it fixes, with severity, CVSS, and CISA KEV status. Cross-linked to the CVE reference.

2026-09-22 16:48 UTC
March 10, 2026—Hotpatch KB5079420 (OS Builds 26200.7979 and 26100.7979 ...

web:support.microsoft.com

This Hotpatch update for Windows 11, version 25H2 and 24H2 (KB5079420), improves functionality, performance, and reliability. To learn more about differences between security updates, optional non-security preview updates, out-of-band (OOB) updates, and continuous innovation, see Windows monthly updates explained. For information on Windows update terminology, see the different types of ...

2026-09-22 16:48 UTC
Microsoft August 2026 Patch Tuesday fixes 400 flaws, 3 zero-days

web:www.bleepingcomputer.com

Today is Microsoft's August 2026 Patch Tuesday, and with it comes security updates for a massive 400 flaws, including one actively exploited and two publicly disclosed zero-day vulnerabilities.

2026-09-22 16:48 UTC
June 2026 Patch Tuesday: Updates and Analysis | CrowdStrike

web:www.crowdstrike.com

Microsoft patches 206 vulnerabilities in June 2026 Patch Tuesday, including three publicly disclosed zero-days.

2026-09-22 16:48 UTC
Microsoft Technical Security Notifications

web:www.microsoft.com

Microsoft's free Security Update Guide Notifications provide links to security-related software updates and notification of re-released security updates. These notifications are sent via email throughout the month as needed. You can choose the type of updates for which you want to be notified: Major ...

2026-09-22 16:48 UTC
Oracle Critical Patch Update Advisory - April 2026

web:www.oracle.com

This Critical Patch Update contains 481 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at April 2026 Critical Patch Update: Executive Summary and Analysis.

2026-09-22 16:48 UTC
Oracle Critical Patch Update Advisory - July 2026

web:www.oracle.com

This Critical Patch Update contains 1448 new security patches across the product families listed below. Please note that a My Oracle Support (MOS) note summarizing the content of this Critical Patch Update and other Oracle Software Security Assurance activities is located at July 2026 Critical Patch Update: Executive Summary and Analysis.

2026-09-22 16:48 UTC
Patch Tuesday September 2026: Security Updates & CVE Analysis

web:zecurit.com

Get the complete breakdown of Microsoft's September 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

2026-09-22 16:48 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-55210.json.

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "joplin",
          "vendor": "laurent22",
          "versions": [
            {
              "status": "affected",
              "version": "< 3.7.2"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.4,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-290",
              "description": "CWE-290: Authentication Bypass by Spoofing",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-21T21:14:31.267Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/laurent22/joplin/security/advisories/GHSA-5px3-4f5x-hjc5",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/laurent22/joplin/security/advisories/GHSA-5px3-4f5x-hjc5"
        },
        {
          "name": "https://github.com/laurent22/joplin/pull/15647",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/laurent22/joplin/pull/15647"
        },
        {
          "name": "https://github.com/laurent22/joplin/commit/b6d69d072919cbe769234f93d95ed21e1ec129b2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/laurent22/joplin/commit/b6d69d072919cbe769234f93d95ed21e1ec129b2"
        }
      ],
      "source": {
        "advisory": "GHSA-5px3-4f5x-hjc5",
        "discovery": "UNKNOWN"
      },
      "title": "Joplin: SAML SSO account takeover via email-based account linking (missing is_external check in ssoLogin)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55210",
    "datePublished": "2026-09-21T21:14:31.267Z",
    "dateReserved": "2026-06-16T16:16:32.627Z",
    "dateUpdated": "2026-09-21T21:14:31.267Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}