CVE-2026-72856 — Budibase versions before 3.40.0 contain an authorization/authentication bypass in the PUT…¶

Key facts

CVE-2026-72856 is a High (8.1) vulnerability: Budibase versions before 3.40.0 contain an authorization/authentication bypass in the PUT…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-72856
Severity	High (8.1)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-72856/

Details¶

English | 한국어

Description¶

Budibase versions before 3.40.0 contain an authorization/authentication bypass in the PUT /api/global/users/tenant/owner (changeTenantOwnerEmail) endpoint. On self-hosted instances (SELF_HOSTED or DISABLE_ACCOUNT_PORTAL set), the cloudRestricted middleware is a no-op and the route is protected only by a general authentication check, so any authenticated user — including a lowest-privilege BASIC app user — can reassign the tenant account-holder (top-privilege admin) email to an attacker-controlled address. The attacker can then use the public password-reset flow to take over the admin account, leading to full administrative access.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-72856
CVSS Score	8.1

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-72856/poc.py

Usage¶

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab¶

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start¶

# Clone and navigate to CVE directory
cd CVE-2026-72856

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints¶

Application	URL	Status
Vulnerable App	http://localhost:8080	Shows vulnerability
Patched App	http://localhost:8081	Demonstrates fix

Directory Structure¶

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References¶

https://github.com/Budibase/budibase/security/advisories/GHSA-j82g-67x3-xcwh
https://www.vulncheck.com/advisories/budibase-before-authentication-bypass-via-tenant-owner-email

Generated by PoC Generator on 2026-08-15T14:02:24.102604609

Frequently asked questions¶

What is CVE-2026-72856?¶

CVE-2026-72856 is a High (8.1) vulnerability: Budibase versions before 3.40.0 contain an authorization/authentication bypass in the PUT…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-72856?¶

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2026-72856?¶

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

For authorized security testing and research only. See the full source and NVD record.