CVE-2026-54356: @budibase/server Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6x9p-4r67-5gjx",
  "modified" : "2026-08-26T14:07:26Z",
  "published" : "2026-08-26T14:07:26Z",
  "aliases" : [ "CVE-2026-54356" ],
  "summary" : "Budibase authenticated arbitrary S3 signed upload URL issuance via `/api/attachments/:datasourceId/url`",
  "details" : "### Summary\nBudibase 3.39.7 allows a low-privilege authenticated published-app user with the built-in BASIC role to obtain arbitrary S3 pre-signed upload URLs backed by a workspace datasource's stored server-side credentials.\n\nThe affected endpoint is:\n\n`POST /api/attachments/:datasourceId/url`\n\nThe caller can control:\n```text\nbucket\nkey\n```\nand receives:\n```text\nsignedUrl\npublicUrl\n```\n\nThis lets a low-privilege published-app user mint S3 `PUT` URLs using server-side datasource credentials for attacker-chosen object destinations.\n\nSteps:\n\n1. Log in as an admin user.\n2. Create a new app/workspace.\n3. In the development app context, create an S3 datasource with valid credentials.\n4. Publish the app.\n5. Create a low-privilege user with the built-in BASIC role on the published production app ID.\n6. Log in as that BASIC user.\n7. Send:\n`POST /api/attachments/<datasourceId>/url`\n\nwith:\n```json\n{\"bucket\":\"foo\",\"key\":\"bar\"}\n```\nand the published app header:\n```text\nx-budibase-app-id: <published_app_id>\n```\nObserve a successful response containing:\n```text\nsignedUrl\npublicUrl\n```\n\n### Observed result\n\nThe following behavior:\n\ndev BASIC request: 403 User does not have permission\napp publish: SUCCESS\nprod BASIC request: 200 OK\nExample confirmed runtime values from the final successful run:\n```text\nprodAppId: app_e6b4cdc6cd6949969a83ff11eee88c5a\ndatasourceId: datasource_0cec491b26a742468257c62382aa3284\npublicUrl: https://foo.s3.eu-west-1.amazonaws.com/bar\n```\nThe returned signedUrl contained standard AWS signing markers, including:\n```text\nX-Amz-Credential=bb\nX-Amz-Signature\nX-Amz-Expires=900\n```\n### Impact\n\nA low-privilege published-app user who knows a valid datasource ID can mint S3 upload URLs backed by server-side datasource credentials and choose arbitrary destination bucket and key values.\n\n### Route definition\n`packages/server/src/api/routes/static.ts:45`\nAuthorization logic\n`packages/server/src/middleware/authorized.ts`\n`packages/server/src/middleware/resourceId.ts`\nController logic\n`packages/server/src/api/controllers/static/index.ts`\nDatasource lookup\n`packages/server/src/sdk/workspace/datasources/datasources.ts`",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@budibase/server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "3.38.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/Budibase/budibase/security/advisories/GHSA-6x9p-4r67-5gjx"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-54356"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Budibase/budibase"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Budibase/budibase/releases/tag/3.41.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-862" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-08-26T14:07:26Z",
    "nvd_published_at" : "2026-08-17T21:16:46Z"
  }
}