CRITICAL CVSS 9.4
Published: 2026-06-26

CVE-2026-50137

budibase budibase Security Advisory (CVE-2026-50137)
↗ Official NIST NVD Record
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CyberVault Technical Summary

Analyst Synthesis

Technical analysis, exploit verification, and patch instructions for CVE-2026-50137 impacting budibase budibase. Evaluated with CVSS Base Score of 9.4 (CRITICAL).

Original NVD Description

Source: NIST NVD
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 explicitly allows anonymous requests. The currentWorkspace middleware's "deny access to dev preview" branch only triggers under isBrowser(ctx) && !isApiKey(ctx); isBrowser checks the parsed User-Agent for a recognised browser, so any non-browser client (curl, the supplied PoC, any tool not setting a browser UA) is neither and reaches dev workspaces too. This vulnerability is fixed in 3.39.0.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Unchanged (S:U)
Confined to same security context
Confidentiality
High (C:H)
Total information disclosure
Integrity
High (I:H)
Total modification of target system
Availability
Low (A:L)
Partial service performance degradation

🎯 Affected Versions Matrix

Affected Product budibase / budibase
Affected Versions *
Weakness Enumeration CWE-862

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2026-50137 impacting budibase budibase.

⚡ Nuclei Detection Template (YAML) cve-2026-50137.yaml
id: cve-2026-50137

info:
  name: budibase budibase - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2026-50137 affecting budibase budibase.
    Evaluation: 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-sou...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2026-50137
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
    cvss-score: 9.4
    cve-id: CVE-2026-50137
    cwe-id: CWE-862
  tags: cve,cve-2026-50137,budibase,budibase,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "budibase"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2026-50137.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2026-50137
# Target: budibase budibase | CVSS: 9.4 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2026-50137 (budibase budibase)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against budibase budibase scope (*).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2026-50137.sh
# Recommended Remediation & Patching Commands for CVE-2026-50137
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install budibase 2>/dev/null || \
sudo dnf upgrade budibase 2>/dev/null || \
sudo yum update budibase

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i budibase 2>/dev/null || rpm -qa | grep -i budibase

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

🔗 Verified Technical References

Authorities
  • No records filed in this category.
Distributions
  • No records filed in this category.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2026-50137 in budibase budibase?

Review vendor-specific security notices and update budibase budibase packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2026-50137?

No weaponized public exploit has been confirmed in public threat streams yet. Continuous surveillance is active across GitHub and security feeds.

What is the CVSS 3.1 severity rating and impact for CVE-2026-50137?

CVE-2026-50137 is classified with a CVSS 3.1 Base Score of 9.4 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
9.4
CRITICAL SEVERITY
CVE ID CVE-2026-50137
Weakness CWE-862
Vendor budibase
Product budibase
Published 2026-06-26
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L