Vulnerability-Lookup

CVE-2026-50136 (GCVE-0-2026-50136)

Vulnerability from cvelistv5 – Published: 2026-06-26 20:36 – Updated: 2026-06-27 03:14

Title

Budibase: Unauthenticated S3 signed upload URL generation allows arbitrary writes with stored datasource credentials

Summary

Budibase is an open-source low-code platform. Prior to 3.39.3, 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. This vulnerability is fixed in 3.39.3.

Severity

7.4 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-27 03:14 UTC

CWE

CWE-306 - Missing Authentication for Critical Function

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/Budibase/budibase/security/adv…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
Budibase	budibase	Affected: < 3.39.3	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-50136

Vulnerability from fkie_nvd - Published: 2026-06-26 21:16 - Updated: 2026-06-30 19:40

Severity

7.4 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/Budibase/budibase/security/advisories/GHSA-jj36-r9w3-3pfh	Exploit, Vendor Advisory
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/Budibase/budibase/security/advisories/GHSA-jj36-r9w3-3pfh	Exploit, Vendor Advisory

Impacted products

	Vendor	Product	Version
	budibase	budibase	*

JSON

To clipboard

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          "product": "budibase",
          "vendor": "Budibase",
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GHSA-JJ36-R9W3-3PFH

Vulnerability from github – Published: 2026-06-22 23:15 – Updated: 2026-07-17 16:59

Summary

Budibase: Unauthenticated S3 signed upload URL generation allows arbitrary writes with stored datasource credentials

Details

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:

Create or identify a workspace with an S3 datasource.
Obtain the production workspace ID and S3 datasource ID.
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"}

Observe that the response contains a signed PUT URL.
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.

Severity

7.4 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L

Show details on source website

JSON

To clipboard

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      "package": {
        "ecosystem": "npm",
        "name": "@budibase/server"
      },
      "ranges": [
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            {
              "fixed": "3.39.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-50136"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-306"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-22T23:15:10Z",
    "nvd_published_at": "2026-06-26T21:16:34Z",
    "severity": "HIGH"
  },
  "details": "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.\n\n### Details\n\nThe static route registers the signed upload URL endpoint with only `recaptcha` before the controller:\n\n- `packages/server/src/api/routes/static.ts:44-48`\n\n```ts\n44:  .post(\n45:    \"/api/attachments/:datasourceId/url\",\n46:    recaptcha,\n47:    controller.getSignedUploadURL\n48:  )\n```\n\nThe controller loads the datasource by `datasourceId` with enriched secret values:\n\n- `packages/server/src/api/controllers/static/index.ts:590-598`\n\n```ts\n590:export const getSignedUploadURL = async function (\n591:  ctx: Ctx\u003cGetSignedUploadUrlRequest, GetSignedUploadUrlResponse\u003e\n592:) {\n593:  // Ensure datasource is valid\n594:  let datasource\n595:  try {\n596:    const { datasourceId } = ctx.params\n597:    datasource = await sdk.datasources.get(datasourceId, { enriched: true })\n598:    if (!datasource) {\n```\n\nThe request body controls `bucket` and `key`, and the server signs a PUT URL using the stored datasource credentials:\n\n- `packages/server/src/api/controllers/static/index.ts:609-629`\n\n```ts\n609:  if (datasource?.source === \"S3\") {\n610:    const { bucket, key } = ctx.request.body || {}\n611:    if (!bucket || !key) {\n612:      ctx.throw(400, \"bucket and key values are required\")\n613:    }\n614:    try {\n615:      let endpoint = datasource?.config?.endpoint\n616:      if (endpoint \u0026\u0026 !utils.urlHasProtocol(endpoint)) {\n617:        endpoint = `https://${endpoint}`\n618:      }\n619:      const s3 = new S3({\n620:        region: awsRegion,\n621:        endpoint: endpoint,\n622:        credentials: {\n623:          accessKeyId: datasource?.config?.accessKeyId as string,\n624:          secretAccessKey: datasource?.config?.secretAccessKey as string,\n625:        },\n626:      })\n627:      const params = { Bucket: bucket, Key: key }\n628:      signedUrl = await getSignedUrl(s3, new PutObjectCommand(params))\n629:      if (endpoint) {\n```\n\nThe endpoint returns the signed URL and public URL to the caller:\n\n- `packages/server/src/api/controllers/static/index.ts:630-639`\n\n```ts\n630:        publicUrl = `${endpoint}/${bucket}/${key}`\n631:      } else {\n632:        publicUrl = `https://${bucket}.s3.${awsRegion}.amazonaws.com/${key}`\n633:      }\n634:    } catch (error: any) {\n635:      ctx.throw(400, error)\n636:    }\n637:  }\n638:\n639:  ctx.body = { signedUrl, publicUrl }\n```\n\nBecause no authorization middleware is applied, the API trusts public input to choose where the stored S3 credentials will write.\n\n### PoC\n\nNon-destructive validation approach:\n\n1. Create or identify a workspace with an S3 datasource.\n2. Obtain the production workspace ID and S3 datasource ID.\n3. Send an unauthenticated request with the workspace ID header and attacker-controlled bucket/key:\n\n```http\nPOST /api/attachments/\u003cdatasourceId\u003e/url HTTP/1.1\nx-budibase-app-id: app_\u003cworkspace-id\u003e\ncontent-type: application/json\n\n{\"bucket\":\"attacker-controlled-or-permitted-bucket\",\"key\":\"poc/budibase.txt\"}\n```\n\n4. Observe that the response contains a signed PUT URL.\n5. Upload harmless content to the returned `signedUrl` and confirm the object is created using the datasource\u0027s stored S3 credentials.\n\n### Impact\n\nThis 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\u0027s cloud credentials.",
  "id": "GHSA-jj36-r9w3-3pfh",
  "modified": "2026-07-17T16:59:09Z",
  "published": "2026-06-22T23:15:10Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Budibase/budibase/security/advisories/GHSA-jj36-r9w3-3pfh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-50136"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Budibase/budibase/pull/18774"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Budibase/budibase/commit/d9dbb7f6105373cc88ecacdbcab70c776f7dd6a1"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Budibase/budibase"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Budibase: Unauthenticated S3 signed upload URL generation allows arbitrary writes with stored datasource credentials"
}

WID-SEC-W-2026-1714

Vulnerability from csaf_certbund - Published: 2026-05-27 22:00 - Updated: 2026-06-28 22:00

Summary

Budibase: Mehrere Schwachstellen ermöglichen Manipulation von Dateien

Severity

Hoch

Scope

2 vulnerabilities in this advisory, including CVE-2026-50136.

CVE-2026-50136

Known affected: 2 products

Open the full advisory

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-50136 (GCVE-0-2026-50136)

FKIE_CVE-2026-50136

GHSA-JJ36-R9W3-3PFH

Details

PoC

Impact

WID-SEC-W-2026-1714

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Sightings

Nomenclature

Related by attack behaviour