Simple Machines Forum < 2.1.7 Authorization Confusion via Profile::load()

{
  "id": "7f9fcafddae5498fb9fc6e67a3a1e1b272bcbe394a85163e8213105bac754996",
  "url": "https://osv.dev/vulnerability/CVE-2026-43621",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Simple Machines Forum < 2.1.7 Authorization Confusion via Profile::load()",
    "summary": "Simple Machines Forum (SMF) through 2.1.7, fixed in commit 6f0dc61, contains an authorization state-confusion vulnerability in the profile loader that allows authenticated low-privileged users to gain administrator access by supplying multiple values for the user parameter. Attackers can exploit the mismatch between Profile::$member and User::$me->is_owner during sequential profile loading to be treated as the owner of an administrator profile, enabling unauthorized password changes and full account takeover.",
    "evidence": "osv:CVE-2026-43621",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-43621",
      "aliases": [
        "CVE-2026-43621"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/simplemachines/smf",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "6f0dc61958aa86a4b436a222f6176812ed5bbb95"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "last_affected": "2.1.7"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  },
                  {
                    "range": [
                      {
                        "fixed": "6f0dc61958aa86a4b436a222f6176812ed5bbb95"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v3.0-alpha.4",
            "v3.0-alpha.3",
            "v3.0-alpha.2",
            "v3.0-alpha.1",
            "v2.1.4",
            "v2.1.3",
            "v2.1.2",
            "v2.1.1",
            "v2.1.0",
            "v2.1-rc.4",
            "v2.1-rc.3",
            "v2.1-rc.2",
            "v2.1-rc.1",
            "v2.1-beta.3",
            "v2.1-beta.2",
            "v2.1-beta.1",
            "2.1beta1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43621.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.612960979Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43621.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-43621",
        "https://www.vulncheck.com/advisories/simple-machines-forum-authorization-confusion-via-profile-load",
        "https://github.com/SimpleMachines/SMF/commit/6f0dc61958aa86a4b436a222f6176812ed5bbb95",
        "https://github.com/SimpleMachines/SMF"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-863"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43621.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-43621",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517962,
  "published_at": "2026-08-26T21:27:52.842+00:00"
}