CVE-2026-3473 (GCVE-0-2026-3473)
Vulnerability from cvelistv5
Published
2026-05-22 10:27
Modified
2026-05-22 12:12
CWE
  • CWE-639 - Authorization Bypass Through User-Controlled Key
Summary
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate file ownership and access control, which allows an authenticated user to access and download files belonging to other users or teams via crafted Boards API requests using valid file IDs.. Mattermost Advisory ID: MMSA-2026-00620
References
Impacted products
Vendor Product Version
Mattermost Mattermost Version: 11.6.0    11.6.0
Version: 11.5.0    11.5.3
Version: 11.4.0    11.4.4
Version: 10.11.0    10.11.14
Create a notification for this product.
Show details on NVD website


{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-3473",
                "options": [
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                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-22T12:12:41.198607Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
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        "providerMetadata": {
          "dateUpdated": "2026-05-22T12:12:49.437Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
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          "vendor": "Mattermost",
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            {
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              "version": "11.6.1"
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            {
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              "version": "11.5.4"
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        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "LOW",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N",
            "version": "3.1"
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          "scenarios": [
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      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-639",
              "description": "CWE-639: Authorization Bypass Through User-Controlled Key",
              "lang": "en",
              "type": "CWE"
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      "providerMetadata": {
        "dateUpdated": "2026-05-22T10:27:02.600Z",
        "orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
        "shortName": "Mattermost"
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      "references": [
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          "tags": [
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          "url": "https://mattermost.com/security-updates"
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      "solutions": [
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          "lang": "en",
          "value": "Update Mattermost to versions 11.7.0, 11.6.1, 11.5.4, 11.4.5, 10.11.15 or higher."
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      ],
      "source": {
        "advisory": "MMSA-2026-00620",
        "defect": [
          "https://mattermost.atlassian.net/browse/MM-67759"
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        "discovery": "EXTERNAL"
      },
      "title": "Improper file ownership validation in the Boards API allows unauthorised file access",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
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    "assignerShortName": "Mattermost",
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    "datePublished": "2026-05-22T10:27:02.600Z",
    "dateReserved": "2026-03-03T12:57:13.379Z",
    "dateUpdated": "2026-05-22T12:12:49.437Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
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