Vulnerability-Lookup

GHSA-2XF7-HMF6-P64J

Vulnerability from github – Published: 2026-02-13 12:31 – Updated: 2026-02-13 20:55

Summary

Mattermost doesn't properly validate channel membership at the time of data retrieval

Details

Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549

Severity ?

3.1 (Low)


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

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 10.11.9"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "10.11.0"
            },
            {
              "fixed": "10.11.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-20796"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-13T20:55:54Z",
    "nvd_published_at": "2026-02-13T11:16:10Z",
    "severity": "LOW"
  },
  "details": "Mattermost versions 10.11.x \u003c= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549",
  "id": "GHSA-2xf7-hmf6-p64j",
  "modified": "2026-02-13T20:55:54Z",
  "published": "2026-02-13T12:31:21Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-20796"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mattermost/mattermost"
    },
    {
      "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:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Mattermost doesn\u0027t properly validate channel membership at the time of data retrieval"
}

CVE-2026-20796 (GCVE-0-2026-20796)

Vulnerability from cvelistv5 – Published: 2026-02-13 10:30 – Updated: 2026-02-13 17:02

Title

Time-of-check time-of-use vulnerability in common teams API

Summary

Severity ?

3.1 (Low)


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

CWE

CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition

Assigner

Mattermost

References

URL

Tags

https://mattermost.com/security-updates

vendor-advisory

Impacted products

	Vendor	Product	Version
	Mattermost	Mattermost	Affected: 10.11.0 , ≤ 10.11.9 (semver) Unaffected: 11.3.0 Unaffected: 10.11.10

Credits

Juho Forsén

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-20796",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-02-13T17:01:37.056493Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-02-13T17:02:25.985Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Mattermost",
          "vendor": "Mattermost",
          "versions": [
            {
              "lessThanOrEqual": "10.11.9",
              "status": "affected",
              "version": "10.11.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "11.3.0"
            },
            {
              "status": "unaffected",
              "version": "10.11.10"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Juho Fors\u00e9n"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Mattermost versions 10.11.x \u003c= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 3.1,
            "baseSeverity": "LOW",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-367",
              "description": "CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-13T10:30:03.445Z",
        "orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
        "shortName": "Mattermost"
      },
      "references": [
        {
          "name": "MMSA-2025-00549",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://mattermost.com/security-updates"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Update Mattermost to versions 11.3.0, 10.11.10 or higher."
        }
      ],
      "source": {
        "advisory": "MMSA-2025-00549",
        "defect": [
          "https://mattermost.atlassian.net/browse/MM-66423"
        ],
        "discovery": "{\"self\"=\u003e\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=\u003e\"Internal\", \"id\"=\u003e\"10557\"}"
      },
      "title": "Time-of-check time-of-use vulnerability in common teams API"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
    "assignerShortName": "Mattermost",
    "cveId": "CVE-2026-20796",
    "datePublished": "2026-02-13T10:30:03.445Z",
    "dateReserved": "2026-01-15T11:34:00.225Z",
    "dateUpdated": "2026-02-13T17:02:25.985Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

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-2XF7-HMF6-P64J

CVE-2026-20796 (GCVE-0-2026-20796)

Tags

Sightings

Nomenclature