Vulnerability Database

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Total vulnerabilities in the database

CVE-2026-50136 — @budibase / server

The application server exposes an unauthenticated endpoint that generates S3 PutObject presigned URLs using credentials stored in a workspace datasource. The route is protected only by the recaptcha middleware and does not require authentication, table permission, datasource permission, or builder access. A public caller who knows a workspace ID and S3 datasource ID can request a signed upload URL for attacker-controlled bucket and key values.

Details

The static route registers the signed upload URL endpoint with only recaptcha before the controller:

  • packages/server/src/api/routes/static.ts:44-48
44: .post( 45: "/api/attachments/:datasourceId/url", 46: recaptcha, 47: controller.getSignedUploadURL 48: )

The controller loads the datasource by datasourceId with enriched secret values:

  • packages/server/src/api/controllers/static/index.ts:590-598
590:export const getSignedUploadURL = async function ( 591: ctx: Ctx<GetSignedUploadUrlRequest, GetSignedUploadUrlResponse> 592:) { 593: // Ensure datasource is valid 594: let datasource 595: try { 596: const { datasourceId } = ctx.params 597: datasource = await sdk.datasources.get(datasourceId, { enriched: true }) 598: if (!datasource) {

The request body controls bucket and key, and the server signs a PUT URL using the stored datasource credentials:

  • packages/server/src/api/controllers/static/index.ts:609-629
609: if (datasource?.source === "S3") { 610: const { bucket, key } = ctx.request.body || {} 611: if (!bucket || !key) { 612: ctx.throw(400, "bucket and key values are required") 613: } 614: try { 615: let endpoint = datasource?.config?.endpoint 616: if (endpoint && !utils.urlHasProtocol(endpoint)) { 617: endpoint = `https://${endpoint}` 618: } 619: const s3 = new S3({ 620: region: awsRegion, 621: endpoint: endpoint, 622: credentials: { 623: accessKeyId: datasource?.config?.accessKeyId as string, 624: secretAccessKey: datasource?.config?.secretAccessKey as string, 625: }, 626: }) 627: const params = { Bucket: bucket, Key: key } 628: signedUrl = await getSignedUrl(s3, new PutObjectCommand(params)) 629: if (endpoint) {

The endpoint returns the signed URL and public URL to the caller:

  • packages/server/src/api/controllers/static/index.ts:630-639
630: publicUrl = `${endpoint}/${bucket}/${key}` 631: } else { 632: publicUrl = `https://${bucket}.s3.${awsRegion}.amazonaws.com/${key}` 633: } 634: } catch (error: any) { 635: ctx.throw(400, error) 636: } 637: } 638: 639: ctx.body = { signedUrl, publicUrl }

Because no authorization middleware is applied, the API trusts public input to choose where the stored S3 credentials will write.

PoC

Non-destructive validation approach:

  1. Create or identify a workspace with an S3 datasource.
  2. Obtain the production workspace ID and S3 datasource ID.
  3. Send an unauthenticated request with the workspace ID header and attacker-controlled bucket/key:
POST /api/attachments/<datasourceId>/url HTTP/1.1 x-budibase-app-id: app_<workspace-id> content-type: application/json {"bucket":"attacker-controlled-or-permitted-bucket","key":"poc/budibase.txt"}
  1. Observe that the response contains a signed PUT URL.
  2. Upload harmless content to the returned signedUrl and confirm the object is created using the datasource's stored S3 credentials.

Impact

This allows unauthenticated arbitrary object writes wherever the stored S3 datasource credentials have PutObject access. Depending on the datasource permissions, this can corrupt application data, overwrite public assets, place attacker-controlled objects in trusted buckets, consume storage, or abuse an organization's cloud credentials.

CVSS v3:

  • Severity: High
  • Score: 7.4
  • AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L

No CWE or OWASP classifications available.

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

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Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

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