GHSA-6X9P-4R67-5GJX

Vulnerability from github – Published: 2026-08-26 14:07 – Updated: 2026-08-26 14:07
VLAI
Summary
Budibase authenticated arbitrary S3 signed upload URL issuance via `/api/attachments/:datasourceId/url`
Details

Summary

Budibase 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.

The affected endpoint is:

POST /api/attachments/:datasourceId/url

The caller can control:

bucket
key

and receives:

signedUrl
publicUrl

This lets a low-privilege published-app user mint S3 PUT URLs using server-side datasource credentials for attacker-chosen object destinations.

Steps:

  1. Log in as an admin user.
  2. Create a new app/workspace.
  3. In the development app context, create an S3 datasource with valid credentials.
  4. Publish the app.
  5. Create a low-privilege user with the built-in BASIC role on the published production app ID.
  6. Log in as that BASIC user.
  7. Send: POST /api/attachments/<datasourceId>/url

with:

{"bucket":"foo","key":"bar"}

and the published app header:

x-budibase-app-id: <published_app_id>

Observe a successful response containing:

signedUrl
publicUrl

Observed result

The following behavior:

dev BASIC request: 403 User does not have permission app publish: SUCCESS prod BASIC request: 200 OK Example confirmed runtime values from the final successful run:

prodAppId: app_e6b4cdc6cd6949969a83ff11eee88c5a
datasourceId: datasource_0cec491b26a742468257c62382aa3284
publicUrl: https://foo.s3.eu-west-1.amazonaws.com/bar

The returned signedUrl contained standard AWS signing markers, including:

X-Amz-Credential=bb
X-Amz-Signature
X-Amz-Expires=900

Impact

A 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.

Route definition

packages/server/src/api/routes/static.ts:45 Authorization logic packages/server/src/middleware/authorized.ts packages/server/src/middleware/resourceId.ts Controller logic packages/server/src/api/controllers/static/index.ts Datasource lookup packages/server/src/sdk/workspace/datasources/datasources.ts

Severity
7.1 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L
Show details on source website
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{
  "affected": [
    {
      "package": {
        "ecosystem": "npm",
        "name": "@budibase/server"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "3.38.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54356"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-862"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-26T14:07:26Z",
    "nvd_published_at": "2026-08-17T21:16:46Z",
    "severity": "HIGH"
  },
  "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\u0027s 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/\u003cdatasourceId\u003e/url`\n\nwith:\n```json\n{\"bucket\":\"foo\",\"key\":\"bar\"}\n```\nand the published app header:\n```text\nx-budibase-app-id: \u003cpublished_app_id\u003e\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`",
  "id": "GHSA-6x9p-4r67-5gjx",
  "modified": "2026-08-26T14:07:26Z",
  "published": "2026-08-26T14:07:26Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Budibase authenticated arbitrary S3 signed upload URL issuance via `/api/attachments/:datasourceId/url`"
}



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