CVE-2026-55210 (GCVE-0-2026-55210)

Vulnerability from cvelistv5 – Published: 2026-09-21 21:14 – Updated: 2026-09-21 21:14
VLAI
Title
Joplin: SAML SSO account takeover via email-based account linking (missing is_external check in ssoLogin)
Summary
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.
Severity
7.4 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-290 - Authentication Bypass by Spoofing
Assigner
References
Impacted products
Vendor Product Version CPE status
laurent22 joplin Affected: < 3.7.2
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "joplin",
          "vendor": "laurent22",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 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\u0027s UserModel.ssoLogin() returns an existing account matched by an IdP-asserted email without checking the account\u0027s is_external flag. In deployments using mixed local and SAML authentication, an attacker whose IdP session can assert a local user\u0027s email can pass POST /api/saml, receive a session for that local account, and access or modify the victim\u0027s 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",
  "vulnerability-lookup:meta": {
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "joplin",
                "vendor": "laurent22",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003c 3.7.2"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "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\u0027s UserModel.ssoLogin() returns an existing account matched by an IdP-asserted email without checking the account\u0027s is_external flag. In deployments using mixed local and SAML authentication, an attacker whose IdP session can assert a local user\u0027s email can pass POST /api/saml, receive a session for that local account, and access or modify the victim\u0027s notes, files, and settings without knowing the local password. This issue is fixed in version 3.7.2."
          }
        ],
        "id": "CVE-2026-55210",
        "lastModified": "2026-09-21T22:16:56.890",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "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"
              },
              "exploitabilityScore": 2.2,
              "impactScore": 5.2,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-09-21T22:16:56.890",
        "references": [
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/laurent22/joplin/commit/b6d69d072919cbe769234f93d95ed21e1ec129b2"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/laurent22/joplin/pull/15647"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/laurent22/joplin/security/advisories/GHSA-5px3-4f5x-hjc5"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Received",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-290"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Primary"
          }
        ]
      }
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.