{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
            "extracted_events": [
              {
                "introduced": "11.7.0"
              },
              {
                "fixed": "11.7.11"
              },
              {
                "introduced": "11.9.0"
              },
              {
                "fixed": "11.9.2"
              },
              {
                "introduced": "11.10.0"
              },
              {
                "fixed": "11.10.2"
              }
            ],
            "source": "CPE_RANGE"
          },
          "events": [
            {
              "introduced": "a9e574a82633915f22071f0d7ca2b006f249ec2a"
            },
            {
              "fixed": "062eb3ba0e0f265bd0bc78d8c5ce5df06b7b6bc8"
            },
            {
              "introduced": "583461af10fc9b2aef2871c722fc4376db695832"
            },
            {
              "fixed": "8ed7691c22159afec427468b8a866aeeaf59a12c"
            },
            {
              "introduced": "7f5bffb8cf3977db8237ce10158fa22aa0d2504f"
            },
            {
              "fixed": "3a01fa64e5c292bd2503de37160cae10e10096de"
            }
          ],
          "repo": "https://github.com/mattermost/mattermost",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Mattermost",
    "cwe_ids": [
      "CWE-918"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/96xxx/CVE-2026-96259.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "introduced": "11.9.0"
          },
          {
            "last_affected": "11.9.1"
          },
          {
            "introduced": "11.8.0"
          },
          {
            "last_affected": "11.8.5"
          },
          {
            "introduced": "11.7.0"
          },
          {
            "last_affected": "11.7.10"
          },
          {
            "introduced": "11.10.0"
          },
          {
            "last_affected": "11.10.1"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "details": "Mattermost versions 11.9.x \u003c= 11.9.1, 11.8.x \u003c= 11.8.5, 11.7.x \u003c= 11.7.10, 11.10.x \u003c= 11.10.1 fail to apply the internal-connection filter to OAuth endpoint requests, which allows a System Administrator to make the server issue requests to internal network addresses and read the responses via the configured OAuth token and userinfo endpoints.. Mattermost Advisory ID: MMSA-2026-00776",
  "id": "CVE-2026-96259",
  "modified": "2026-10-09T02:30:37.726943728Z",
  "published": "2026-09-22T20:34:20.872Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/96xxx/CVE-2026-96259.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://mattermost.com/security-updates"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-96259"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Mattermost server-side request forgery via OAuth endpoints configurable by a System Administrator"
}