CVE-2026-107850 (GCVE-0-2026-107850)

Vulnerability from cvelistv5 – Published: 2026-10-09 20:25 – Updated: 2026-10-09 20:25
VLAI
Title
Contao: Improper access control in the preview links module
Summary
Contao is an Open Source CMS. From version 5.7.1 until 5.7.12, core-bundle/config/services.yaml registers the preview access voter as Contao\CoreBundle\Security\Voter\DataContainer\PreviewAccessVoter although the shipped class is PreviewVoter. Symfony therefore omits voter autoconfiguration and removes the private service, so PreviewVoter::hasAccess() never enforces ownership. A non-admin backend user with the preview_link module can list every tl_preview_link record, obtain signed share URLs created by other users, and use them to view unpublished pages with showUnpublished despite lacking page permission. The advisory does not establish editing or deletion of foreign links. This issue is fixed in version 5.7.12.
Severity
4.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CWE
  • CWE-639 - Authorization Bypass Through User-Controlled Key
  • CWE-862 - Missing Authorization
Assigner
GitHub_M CNA under the mitre root
CNA scorecard C 72/100 over 7600 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
contao contao Affected: >= 5.7.1, < 5.7.12
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "contao",
          "vendor": "contao",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 5.7.1, \u003c 5.7.12"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Contao is an Open Source CMS. From version 5.7.1 until 5.7.12, core-bundle/config/services.yaml registers the preview access voter as Contao\\CoreBundle\\Security\\Voter\\DataContainer\\PreviewAccessVoter although the shipped class is PreviewVoter. Symfony therefore omits voter autoconfiguration and removes the private service, so PreviewVoter::hasAccess() never enforces ownership. A non-admin backend user with the preview_link module can list every tl_preview_link record, obtain signed share URLs created by other users, and use them to view unpublished pages with showUnpublished despite lacking page permission. The advisory does not establish editing or deletion of foreign links. This issue is fixed in version 5.7.12."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
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          "descriptions": [
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              "cweId": "CWE-639",
              "description": "CWE-639: Authorization Bypass Through User-Controlled Key",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-862",
              "description": "CWE-862: Missing Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-09T20:25:02.286Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/contao/contao/security/advisories/GHSA-q6wp-fr43-gm9v",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/contao/contao/security/advisories/GHSA-q6wp-fr43-gm9v"
        },
        {
          "name": "https://github.com/contao/contao/commit/6b483d380a4b2dc61432c4c697e411508f93bf91",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/contao/contao/commit/6b483d380a4b2dc61432c4c697e411508f93bf91"
        },
        {
          "name": "https://github.com/contao/contao/releases/tag/5.7.12",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/contao/contao/releases/tag/5.7.12"
        }
      ],
      "source": {
        "advisory": "GHSA-q6wp-fr43-gm9v",
        "discovery": "UNKNOWN"
      },
      "title": "Contao: Improper access control in the preview links module"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-107850",
    "datePublished": "2026-10-09T20:25:02.286Z",
    "dateReserved": "2026-10-08T22:34:49.292Z",
    "dateUpdated": "2026-10-09T20:25:02.286Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-107850",
      "date": "2026-10-10",
      "epss": "0.00193",
      "percentile": "0.08254"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "product": "contao",
                "vendor": "contao",
                "versions": [
                  {
                    "status": "affected",
                    "version": "\u003e= 5.7.1, \u003c 5.7.12"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Contao is an Open Source CMS. From version 5.7.1 until 5.7.12, core-bundle/config/services.yaml registers the preview access voter as Contao\\CoreBundle\\Security\\Voter\\DataContainer\\PreviewAccessVoter although the shipped class is PreviewVoter. Symfony therefore omits voter autoconfiguration and removes the private service, so PreviewVoter::hasAccess() never enforces ownership. A non-admin backend user with the preview_link module can list every tl_preview_link record, obtain signed share URLs created by other users, and use them to view unpublished pages with showUnpublished despite lacking page permission. The advisory does not establish editing or deletion of foreign links. This issue is fixed in version 5.7.12."
          }
        ],
        "id": "CVE-2026-107850",
        "lastModified": "2026-10-09T21:17:02.770",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
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                "baseScore": 4.3,
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                "confidentialityImpact": "LOW",
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                "privilegesRequired": "LOW",
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                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
                "version": "3.1"
              },
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              "impactScore": 1.4,
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-10-09T21:17:02.770",
        "references": [
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            "source": "security-advisories@github.com",
            "url": "https://github.com/contao/contao/commit/6b483d380a4b2dc61432c4c697e411508f93bf91"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/contao/contao/releases/tag/5.7.12"
          },
          {
            "source": "security-advisories@github.com",
            "url": "https://github.com/contao/contao/security/advisories/GHSA-q6wp-fr43-gm9v"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Received",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-639"
              },
              {
                "lang": "en",
                "value": "CWE-862"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Primary"
          }
        ]
      }
    }
  }
}



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