Obsidian Web MCP: Unauthenticated vault access: /oauth/authorize auto-approves without authenticating the user

{
  "id": "ce01a679a960a26dd95fa27e44b38a420605712a72b97831171d3903c33ba5f3",
  "url": "https://osv.dev/vulnerability/CVE-2026-54618",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Obsidian Web MCP: Unauthenticated vault access: /oauth/authorize auto-approves without authenticating the user",
    "summary": "Obsidian Web MCP is a secure remote MCP server for Obsidian vaults. Prior to 0.2.0, /oauth/authorize issues an authorization code without a login, consent, or session check, and /oauth/token can exchange that code for the static VAULT_MCP_TOKEN without authenticating a client. An unauthenticated remote caller who can reach the intended tunnel deployment can therefore call /mcp and use vault_read, vault_write, vault_search, vault_list, vault_move, and vault_delete against the entire vault. Optional PKCE does not prevent an attacker-initiated flow, and unauthenticated /oauth/register also exposes a client_credentials path by returning the configured VAULT_OAUTH_CLIENT_SECRET. This issue is fixed in version 0.2.0.",
    "evidence": "osv:CVE-2026-54618",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-54618",
      "aliases": [
        "CVE-2026-54618",
        "GHSA-hwhg-mrjc-8g43"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/jimprosser/obsidian-web-mcp",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "e4924f096ee7494a7999d6c0cceca9be08e48eef"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.2.0"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e4924f096ee7494a7999d6c0cceca9be08e48eef"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e4924f096ee7494a7999d6c0cceca9be08e48eef"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.2.0"
                  },
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.2.0"
                      }
                    ],
                    "source": "DESCRIPTION"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-54618.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.860786193Z",
      "provider": "osv",
      "references": [
        "https://github.com/jimprosser/obsidian-web-mcp/releases/tag/v0.2.0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54618.json",
        "https://github.com/jimprosser/obsidian-web-mcp/security/advisories/GHSA-hwhg-mrjc-8g43",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-54618",
        "https://github.com/jimprosser/obsidian-web-mcp/commit/e4924f096ee7494a7999d6c0cceca9be08e48eef",
        "https://github.com/jimprosser/obsidian-web-mcp/pull/30"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-306",
          "CWE-522",
          "CWE-601"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/54xxx/CVE-2026-54618.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-54618",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 505257,
  "published_at": "2026-09-17T19:45:15.384+00:00"
}