Vulnerability in @budibase/server (CVE-2026-50137)
Summary
Vulnerability in @budibase/server (CVE-2026-50137). Confidential information can be exposed externally. Exploitable via POST /api/attachments/. Mitigation: upgrade to 3.39.0 or later.
Original description
The description as published by the source.
Budibase is an open-source low-code platform. Prior to 3.39.0, an anonymous attacker who knows or can enumerate a workspace id (app_...) and an S3-source datasource id (ds_...) can call this endpoint with no auth and obtain a 15-minute pre-signed PUT URL minted on the victim's IAM identity. The endpoint also returns the publicUrl so the attacker knows exactly where their PUT lands. Because bucket is attacker-controlled, the attacker can write to any bucket those IAM credentials can write to, not only the bucket the datasource was configured for. The Budibase server route POST /api/attachments/:datasourceId/url (packages/server/src/api/routes/static.ts) is registered with only the recaptcha middleware. There is no authorized(...) middleware in the chain. The controller (packages/server/src/api/controllers/static/index.ts::getSignedUploadURL) looks the requested datasource up, instantiates an AWS S3 client with the datasource's stored accessKeyId / secretAccessKey, and returns an AWS Signature V4 pre-signed PutObjectCommand URL for the caller-supplied bucket and key. The bucket is not pinned to the datasource's configured bucket. The workspace context required by sdk.datasources.get is sourced by getWorkspaceIdFromCtx (packages/backend-core/src/utils/utils.ts) from any of: the x-budibase-app-id header, the JSON body appId, a path segment that begins with the workspace prefix, or ?appId=. auth.buildAuthMiddleware([], { publicAllowed: true }) runs before any of this and explicitl…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-50137 has been found in @budibase/server.
Attackers can target a specific entry point like POST /api/attachments/ over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 9.4/10.
What to do: upgrade @budibase/server to 3.39.0 or later.
If unsure, ask your IT team or search "@budibase/server CVE-2026-50137" on the vendor's site.
CVE-2026-50137 (@budibase/server) — CWE-862 / CVSS v3 9.4
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: POST /api/attachments/ / POST /api/attachments/ds_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/url / POST /api/attachments/process / POST /api/pwa/process-zip
Patched: 3.39.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-862) exists in @budibase/server. Attackers reach the vulnerable code path via POST /api/attachments/ without authentication.
Check the vendor advisory for the affected versions of @budibase/server. Attack surface: POST /api/attachments/ / POST /api/attachments/ds_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/url / POST /api/attachments/process / POST /api/pwa/process-zip.
Severity: Critical (CVSS 9.4/10). Confidential information can be exposed externally.
Update to 3.39.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual POST /api/attachments/ requests with malformed payloads or SQL meta-characters. Run grep -r '@budibase/server' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r '@budibase/server' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
@budibase/serverを grep し、稼働しているサービス・バージョンを把握する。 -
2Hunt for indicators of compromise detect
grep 'POST /api/attachments/' /var/log/nginx/access.log | grep -E '(unusual_payload|sqli_pattern)'アクセスログで
POST /api/attachments/への異常なリクエスト (不正な認証ヘッダ・SQLメタ文字)を過去 30〜90日分捜索。WAF/SIEM があれば該当パスのアラート発火履歴を確認。 -
3Apply patch patch
Upgrade @budibase/server to 3.39.0ステージング環境で 3.39.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 2 で見つけた異常検知の続報チェックを含めること。
-
4Post-deployment verification verify
Replay attack against POST /api/attachments/ on staging to confirm patch closes the vectorパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 2 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com