Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients

{
  "id": "046b7b9fbbcfe76580c399c995d2d7cd1d36c3fc61b810a1c7f24e8d632850cd",
  "url": "https://osv.dev/vulnerability/CVE-2026-43639",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Bitwarden Server < 2026.4.0 Missing Authorization via Provider Clients",
    "summary": "Bitwarden Server prior to v2026.4.0 contains a missing authorization vulnerability that allows a provider service user to add an arbitrary organization to their provider via `POST /providers/{providerId}/clients/existing`, resulting in takeover of the target organization; self-hosted installations are unaffected as this endpoint is restricted to Cloud via SelfHosted(NotSelfHostedOnly = true).",
    "evidence": "osv:CVE-2026-43639",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-43639",
      "aliases": [
        "CVE-2026-43639"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:H/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/bitwarden/server",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "a2efc7409cea90dfb9ffae309851935f57294f3f"
                },
                {
                  "fixed": "0918bfdda6f5eec391c69bd9074f6aef4eac0b1d"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:bitwarden:server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2026.4.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "0918bfdda6f5eec391c69bd9074f6aef4eac0b1d"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "a2efc7409cea90dfb9ffae309851935f57294f3f"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2026.4.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2025.10.1",
            "v2025.8.1",
            "v2025.7.1",
            "v2024.10.1",
            "v2024.8.1",
            "v2024.8.0",
            "v2024.5.0",
            "v2024.2.3",
            "v2024.1.2",
            "v1.39.0",
            "v1.38.2",
            "v1.38.1",
            "v1.38.0",
            "v1.37.2",
            "v1.37.1",
            "v1.37.0",
            "v1.36.1",
            "v1.36.0",
            "v1.35.1",
            "v1.35.0",
            "v1.34.0",
            "v1.33.1",
            "v1.33.0",
            "v1.32.0",
            "v1.31.1",
            "v1.31.0",
            "v1.30.4",
            "v1.30.3",
            "v1.30.2",
            "v1.30.1",
            "v1.30.0",
            "v1.29.0",
            "v1.28.0",
            "v1.27.0",
            "v1.26.0",
            "v1.25.0",
            "v1.24.0",
            "v1.23.0",
            "1.22.0",
            "v1.21.0",
            "v1.20.0",
            "v1.19.0",
            "v1.18.0",
            "v1.17.2",
            "v1.17.1",
            "v1.17.0",
            "v1.16.0",
            "v1.15.1",
            "v1.15.0",
            "v1.14.2",
            "v1.14.1",
            "v1.14.0",
            "v1.13.1",
            "v1.13.0",
            "v1.12.1",
            "v1.12.0",
            "v1.11.1",
            "v1.11.0",
            "v1.10.0",
            "v1.9.0",
            "v1.8.2",
            "v1.8.1",
            "v1.8.0",
            "v1.7.0",
            "v1.6.0",
            "v1.5.1",
            "v1.5.0",
            "v1.4.1",
            "1.4.0",
            "v1.3.4",
            "v1.3.3",
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.0",
            "v1.1.0",
            "v1.0.3",
            "v1.0.2",
            "v1.0.1",
            "v1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43639.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.458032381Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43639.json",
        "https://github.com/bitwarden/server/releases/tag/v2026.4.0",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-43639",
        "https://www.vulncheck.com/advisories/bitwarden-server-missing-authorization-via-provider-clients",
        "https://github.com/bitwarden/server/pull/7372",
        "https://github.com/bitwarden/server/commit/0918bfdda6f5eec391c69bd9074f6aef4eac0b1d",
        "https://github.com/bitwarden/server",
        "https://sanjokkarki.com.np/blog/bitwarden-provider-takeover"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-862"
        ],
        "cna_assigner": "VulnCheck",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43639.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-43639",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 493745,
  "published_at": "2026-05-11T17:14:04.552+00:00"
}