GHSA-6X9P-4R67-5GJX
Vulnerability from github – Published: 2026-08-26 14:07 – Updated: 2026-08-26 14:07Summary
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:
- Log in as an admin user.
- Create a new app/workspace.
- In the development app context, create an S3 datasource with valid credentials.
- Publish the app.
- Create a low-privilege user with the built-in BASIC role on the published production app ID.
- Log in as that BASIC user.
- 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
{
"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`"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
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- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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