CVE-2026-73304: Budibase SSO OAuth2 Token Leakage Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fcrw-f7gg-6g9f",
  "modified" : "2026-08-12T18:57:12Z",
  "published" : "2026-07-24T21:14:31Z",
  "aliases" : [ "CVE-2026-73304" ],
  "summary" : " Budibase: SSO OAuth2 Token Leakage via User Metadata Endpoints to Power-Role Users",
  "details" : "## Summary\n\nThe `/api/users/metadata` and `/api/users/metadata/:id` endpoints in `@budibase/server` return full global user profiles to any user with POWER role or above. For SSO-authenticated users (OIDC, Google), the response includes `oauth2.accessToken` and `oauth2.refreshToken` fields, leaking identity provider credentials to other users who should not have access to them.\n\n## Details\n\nWhen a user authenticates via SSO (OIDC or Google), the OAuth2 tokens are stored in the global CouchDB user document at `packages/backend-core/src/auth/auth.ts:170-173`:\n\n```typescript\ndbUser.oauth2 = {\n  ...dbUser.oauth2,\n  ...details,\n}\nawait db.put(dbUser)\n```\n\nThe user metadata endpoints are protected by `PermissionType.USER, PermissionLevel.READ` (`packages/server/src/api/routes/user.ts:11`), which maps to the POWER permission set (`packages/backend-core/src/security/permissions.ts:99`).\n\n**Path 1 — List all users** (`GET /api/users/metadata`):\n1. `controller.fetchMetadata` → `sdk.users.fetchMetadata()` (`packages/server/src/sdk/users/utils.ts:78`)\n2. → `getGlobalUsers()` → `getRawGlobalUsers()` (`packages/server/src/utilities/global.ts:101-122`) — strips only `password` and `forceResetPassword`\n3. → `processUser()` (`packages/server/src/utilities/global.ts:15-76`) — strips only `password` and `roles`\n4. The `oauth2` field containing `accessToken` and `refreshToken` is **never removed**\n\n**Path 2 — Single user** (`GET /api/users/metadata/:id`):\n1. `controller.findMetadata` → `getFullUser()` (`packages/server/src/utilities/users.ts:6`)\n2. → `getGlobalUser()` → `getRawGlobalUser()` (`packages/server/src/utilities/global.ts:90-92`) — raw CouchDB fetch, **no field stripping at all**\n3. → `processUser()` — strips only `password` and `roles`\n4. Same result: `oauth2` tokens are returned\n\nThere is no output sanitization middleware on these routes that would strip sensitive fields before the response reaches the client.\n\n## PoC\n\n**Prerequisites:** A Budibase instance with at least one SSO-authenticated user (OIDC or Google) and a separate user with POWER role in an app.\n\n**Step 1 — As the POWER user, list all users:**\n```bash\ncurl -s -X GET 'http://localhost:10000/api/users/metadata' \\\n  -H 'Cookie: budibase:auth=<power-user-jwt>' \\\n  -H 'x-budibase-app-id: app_<appid>' | jq '.[].oauth2'\n```\n\n**Expected output:** `null` for all users (tokens should not be exposed)\n\n**Actual output:** For SSO users, the response includes:\n```json\n{\n  \"accessToken\": \"ya29.a0ARrdaM...\",\n  \"refreshToken\": \"1//0eXxXxXxXx...\"\n}\n```\n\n**Step 2 — Fetch a specific SSO user's profile:**\n```bash\ncurl -s -X GET 'http://localhost:10000/api/users/metadata/ro_ta_users_us_<sso-user-id>' \\\n  -H 'Cookie: budibase:auth=<power-user-jwt>' \\\n  -H 'x-budibase-app-id: app_<appid>' | jq '.oauth2'\n```\n\nThis also returns the full OAuth2 tokens.\n\n## Impact\n\n- A user with POWER role in any app can read **all SSO users' OAuth2 access tokens and refresh tokens** via the list endpoint, without needing to know individual user IDs.\n- Stolen access tokens can be used to access external identity provider resources (Google Workspace, Azure AD, Okta-protected services) as the victim user.\n- Refresh tokens allow indefinite token renewal, persisting access even after the original access token expires.\n- Additionally, `admin`, `builder`, `tenantId`, `ssoId`, and `userGroups` fields are leaked, revealing the full authorization topology of the instance.\n\n## Recommended Fix\n\nStrip sensitive SSO fields in `processUser()` at `packages/server/src/utilities/global.ts:15`:\n\n```typescript\nexport async function processUser(\n  user: ContextUser,\n  opts: { appId?: string; groups?: UserGroup[] } = {}\n) {\n  if (!user || (!user.roles && !user.userGroups)) {\n    return user\n  }\n  user = cloneDeep(user)\n  delete user.password\n+ delete (user as any).oauth2\n+ delete (user as any).provider\n+ delete (user as any).providerType\n+ delete (user as any).thirdPartyProfile\n+ delete (user as any).profile\n+ delete (user as any).ssoId\n+ delete (user as any).forceResetPassword\n  // ... rest of function\n```\n\nAdditionally, `getRawGlobalUsers()` at line 101 should also strip `oauth2` alongside its existing `password`/`forceResetPassword` stripping for defense in depth.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@budibase/server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.39.25"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/Budibase/budibase/security/advisories/GHSA-fcrw-f7gg-6g9f"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Budibase/budibase/pull/19110"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Budibase/budibase/commit/7b8ba11a2c8b233c35e7728dd752dba25ef919a4"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Budibase/budibase/commit/80a31f6c3354620aa90e50af8a2c614333084621"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Budibase/budibase"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Budibase/budibase/releases/tag/3.39.25"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-24T21:14:31Z",
    "nvd_published_at" : null
  }
}