Vulnerability-Lookup

GHSA-2WMQ-3M94-G4JR

Vulnerability from github – Published: 2026-06-15 15:31 – Updated: 2026-06-15 15:31

Details

Mattermost Desktop App versions <=6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that routes to an external web server. Mattermost Advisory ID: MMSA-2026-00651

Severity

6.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-6517"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-522"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-06-15T14:16:37Z",
    "severity": "MODERATE"
  },
  "details": "Mattermost Desktop App versions \u003c=6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that routes to an external web server. Mattermost Advisory ID: MMSA-2026-00651",
  "id": "GHSA-2wmq-3m94-g4jr",
  "modified": "2026-06-15T15:31:33Z",
  "published": "2026-06-15T15:31:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6517"
    },
    {
      "type": "WEB",
      "url": "https://mattermost.com/security-updates"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-6517 (GCVE-0-2026-6517)

Vulnerability from cvelistv5 – Published: 2026-06-15 13:55 – Updated: 2026-06-15 16:00

Title

Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed

Summary

Severity

6.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-522 - Insufficiently Protected Credentials

Assigner

Mattermost

References

1 reference

URL	Tags
https://mattermost.com/security-updates	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
Mattermost	Mattermost	Affected: 0 , ≤ 5.5.13 (semver) Unaffected: 6.2.0 Unaffected: 5.13.6.0

Credits

falke

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-6517",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-15T15:59:27.291763Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-15T16:00:00.919Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Mattermost",
          "vendor": "Mattermost",
          "versions": [
            {
              "lessThanOrEqual": "5.5.13",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.2.0"
            },
            {
              "status": "unaffected",
              "version": "5.13.6.0"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "falke"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Mattermost Desktop App versions \u003c=6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that routes to an external web server. Mattermost Advisory ID: MMSA-2026-00651"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-522",
              "description": "CWE-522: Insufficiently Protected Credentials",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-15T13:55:25.742Z",
        "orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
        "shortName": "Mattermost"
      },
      "references": [
        {
          "name": "MMSA-2026-00651",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://mattermost.com/security-updates"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Update Mattermost Desktop App to versions 6.2.0, 5.13.6.0 or higher."
        }
      ],
      "source": {
        "advisory": "MMSA-2026-00651",
        "defect": [
          "https://mattermost.atlassian.net/browse/MM-68362"
        ],
        "discovery": "EXTERNAL"
      },
      "title": "Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
    "assignerShortName": "Mattermost",
    "cveId": "CVE-2026-6517",
    "datePublished": "2026-06-15T13:55:25.742Z",
    "dateReserved": "2026-04-17T14:25:10.246Z",
    "dateUpdated": "2026-06-15T16:00:00.919Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Action not permitted

GHSA-2WMQ-3M94-G4JR

CVE-2026-6517 (GCVE-0-2026-6517)

Tags

Sightings

Nomenclature