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CVE-2024-39839

Status: AnalyzedMedium (4.3)—

Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5, 9.8.x <= 9.8.1 fail to disallow users to set their own remote username, when shared channels were enabled, which allows a user on a remote to set their remote username prop to an arbitrary string, which would be then synced to the local server as long as the user hadn't been synced before.

CVSS

Exploitation probability (EPSS)

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

Affected technologies (1)

Mattermost — Mattermost Server

CWEs

References

Raw JSON (NVD)

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{
  "id": "CVE-2024-39839",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2024-39839",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2024-08-01T18:04:29.704681Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "responsibledisclosure@mattermost.com",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 2.8
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 4.3,
          "attackVector": "NETWORK",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
          "integrityImpact": "LOW",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 1.4,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "affected": [
    {
      "source": "responsibledisclosure@mattermost.com",
      "affectedData": [
        {
          "vendor": "Mattermost",
          "product": "Mattermost",
          "versions": [
            {
              "status": "affected",
              "version": "9.9.0"
            },
            {
              "status": "affected",
              "version": "9.5.0",
              "versionType": "semver",
              "lessThanOrEqual": "9.5.6"
            },
            {
              "status": "affected",
              "version": "9.7.0",
              "versionType": "semver",
              "lessThanOrEqual": "9.7.5"
            },
            {
              "status": "affected",
              "version": "9.8.0",
              "versionType": "semver",
              "lessThanOrEqual": "9.8.1"
            },
            {
              "status": "unaffected",
              "version": "9.10.0"
            },
            {
              "status": "unaffected",
              "version": "9.9.1"
            },
            {
              "status": "unaffected",
              "version": "9.5.7"
            },
            {
              "status": "unaffected",
              "version": "9.7.6"
            },
            {
              "status": "unaffected",
              "version": "9.8.2"
            }
          ],
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2024-08-01T15:15:12.993",
  "references": [
    {
      "url": "https://mattermost.com/security-updates",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "responsibledisclosure@mattermost.com"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "responsibledisclosure@mattermost.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-284"
        }
      ]
    },
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5, 9.8.x <= 9.8.1 fail to disallow users to set their own remote username, when shared channels were enabled, which allows a user on a remote to set their remote username prop to an arbitrary string, which would be then synced to the local server as long as the user hadn't been synced before."
    },
    {
      "lang": "es",
      "value": " Las versiones de Mattermost 9.9.x &lt;= 9.9.0, 9.5.x &lt;= 9.5.6, 9.7.x &lt;= 9.7.5, 9.8.x &lt;= 9.8.1 no permiten que los usuarios establezcan su propio nombre de usuario remoto cuando se comparte. Se habilitaron canales, lo que permite a un usuario en un control remoto configurar su nombre de usuario remoto en una cadena arbitraria, que luego se sincronizaría con el servidor local siempre que el usuario no se hubiera sincronizado antes."
    }
  ],
  "lastModified": "2026-06-17T07:42:53.883",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "CBEB8F40-C2DE-4E6F-8772-1BBCA44795A8",
              "versionEndExcluding": "9.5.7",
              "versionStartIncluding": "9.5.0"
            },
            {
              "criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "B5C9F963-57DF-41E2-AA46-242317D93786",
              "versionEndExcluding": "9.7.6",
              "versionStartIncluding": "9.7.0"
            },
            {
              "criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "6B4559B7-83E7-41B2-96A8-51F467CCD882",
              "versionEndExcluding": "9.8.2",
              "versionStartIncluding": "9.8.0"
            },
            {
              "criteria": "cpe:2.3:a:mattermost:mattermost_server:9.9.0:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "4BE71910-C7C4-4F33-BFD4-40D2EAA56DB1"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "responsibledisclosure@mattermost.com"
}