CVE-2026-9571 (GCVE-0-2026-9571)

Vulnerability from cvelistv5 – Published: 2026-07-13 07:50 – Updated: 2026-07-13 07:50
VLAI
Title
Deactivated user accounts can continue to obtain valid OAuth access tokens via refresh token grant in Mattermost
Summary
Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to invalidate OAuth refresh tokens upon user account deactivation, which allows a deactivated user or an attacker in possession of a valid refresh token to obtain new functional access tokens via the OAuth refresh token grant endpoint.. Mattermost Advisory ID: MMSA-2026-00680
Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
CWE
  • CWE-305 - – Authentication Bypass by Primary Weakness
Assigner
References
URL Tags
https://mattermost.com/security-updates vendor-advisory
Impacted products
Vendor Product Version
Mattermost Mattermost Affected: 11.7.0 , ≤ 11.7.2 (semver)
Affected: 11.6.0 , ≤ 11.6.4 (semver)
Affected: 10.11.0 , ≤ 10.11.19 (semver)
Unaffected: 11.8.0
Unaffected: 11.7.3
Unaffected: 11.6.5
Unaffected: 10.11.20
Create a notification for this product.
Credits
kirs112
Show details on NVD website
To clipboard 

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            },
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              "status": "unaffected",
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        }
      ],
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            "attackVector": "NETWORK",
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            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "HIGH",
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            "userInteraction": "NONE",
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      "problemTypes": [
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            }
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      "providerMetadata": {
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        "orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
        "shortName": "Mattermost"
      },
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          "tags": [
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      "solutions": [
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          "value": "Update Mattermost to versions 11.8.0, 11.7.3, 11.6.5, 10.11.20 or higher."
        }
      ],
      "source": {
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        "defect": [
          "https://mattermost.atlassian.net/browse/MM-68982"
        ],
        "discovery": "EXTERNAL"
      },
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      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
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    "dateReserved": "2026-05-26T11:52:27.228Z",
    "dateUpdated": "2026-07-13T07:50:55.793Z",
    "state": "PUBLISHED"
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  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.