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Introduction:
A critical Remote Code Execution (RCE) vulnerability affecting Metabase Enterprise Editions has escalated from a concerning bug to an imminent threat following the public release of a fully functional proof-of-concept (PoC) exploit on GitHub. This makes CVE-2026-33725 a high-priority risk for organizations using vulnerable versions of this analytics platform, as the barrier to exploitation has been significantly lowered.
Learning Objectives:
- Understand the technical root cause of CVE-2026-33725 and its impact on Metabase Enterprise environments.
- Learn how to identify, detect, and properly patch vulnerable Metabase instances across your organization.
- Gain practical knowledge of mitigation commands, access controls, and security hardening techniques to protect against exploitation.
You Should Know:
1. Inside the H2 JDBC INIT Injection Vulnerability
CVE-2026-33725 stems from an insecure deserialization weakness (CWE-502) in Metabase Enterprise’s serialization import functionality. The vulnerability enables authenticated administrators to achieve Remote Code Execution (RCE) and read arbitrary files by injecting a malicious INIT property into the H2 JDBC connection string via a crafted serialization archive. When exploited, the H2 database engine processes the injected INIT property during a database synchronization, executing arbitrary SQL that can trigger system commands. The CVSS score reaches 7.2, classified as High severity.
Step-by-step Technical Breakdown:
- An attacker with administrative credentials crafts a malicious serialization archive.
- The archive contains a manipulated database connection specification with an injected INIT property.
- The attacker uploads this archive via the `POST /api/ee/serialization/import` endpoint.
- During the database sync process, the H2 database engine processes the INIT property.
- The injected SQL commands execute with Metabase application privileges, enabling RCE and file read operations.
Commands & Tools Used in Exploitation:
A Python-based PoC script that automates the full attack chain for CVE-2026-33725 has been published by security researcher Diego Tellaroli of Hakai Security on GitHub, making exploitation significantly easier for attackers to replicate. Linux file read and system reconnaissance commands used in post-exploitation include:
Read sensitive system files from compromised host cat /etc/passwd ls -la /home//.ssh/id_rsa Check environment variables for cloud credentials env | grep -E 'AWS|AZURE|GCP' Scan internal network to pivot from compromised Metabase host nmap -sn 10.0.0.0/24
2. Affected Versions and Patching Strategy
All Metabase Enterprise releases with serialization support from version 1.47 onward are vulnerable, including Metabase Cloud instances. Importantly, Metabase Open Source Software (OSS) does NOT contain the vulnerable codepaths and remains unaffected. The patch status dashboard below outlines affected branches and fixed versions.
Step-by-step Patching Guide:
- Identify the current Metabase version by accessing the Admin Panel → Troubleshooting → Version Info, or checking the `version` field in the response from
/api/session/properties.
2. Compare against the patched versions list.
- Download and deploy the patched version (e.g., via Docker image update, JAR replacement, or cloud update mechanism).
- After patching, verify version via the API endpoint:
curl -X GET https://your-metabase-instance.com/api/session/properties | jq '.version'
-
Validate that the serialization import endpoint is no longer vulnerable by attempting a safe test import with a benign archive.
If immediate patching is not feasible, restrict access to the Metabase administration interface, limit exposure to trusted networks, and closely monitor logs for suspicious import or serialization activity. Additionally, as a workaround, disable the serialization import endpoint in your Metabase instance to prevent access to the vulnerable codepaths.
3. Detection and Log Monitoring for Active Exploitation
Organizations should actively monitor their Metabase instances for signs of compromise. Key indicators of compromise include suspicious requests to the `/api/ee/serialization/import` endpoint with unusual archive sizes or unknown sources, unexpected database connection attempts from the Metabase host, anomalous SQL commands executed during sync operations, and unexplained outbound network connections from Metabase.
Step-by-step Detection and Analysis:
- Review Metabase application logs for any `POST /api/ee/serialization/import` requests, especially from unknown IPs.
2. Analyze the `/var/log/metabase/metabase.log` file:
grep -i "serialization/import" /var/log/metabase/metabase.log
- Monitor for unusual process execution triggered by the H2 database engine using process auditing:
Linux process monitoring ps aux | grep -E "java|H2" Windows process monitoring Get-Process | Where-Object {$_.ProcessName -like "java"} -
Check for unauthorized file reads by reviewing system call traces or file access logs:
Linux file access monitoring with auditd auditctl -w /etc/passwd -p r ausearch -f /etc/passwd
-
Run a comprehensive vulnerability scan using specialized scripts:
Nmap script to detect Metabase version nmap -sV --script http-metabase-version -p 3000 target-ip
4. Access Control and API Security Hardening
Since exploitation requires authenticated administrator access, reinforcing administrative account security is crucial. Organizations should enforce strong password policies, implement multi-factor authentication where possible, and rotate administrative credentials regularly. Network segmentation adds another critical layer: restrict access to Metabase via firewalls to trusted IP ranges only, and place the instance behind a reverse proxy with geo-blocking capabilities for the management interface.
Step-by-step Access Hardening:
- Limit Metabase admin interface to specific IP ranges using iptables (Linux) or Windows Firewall (Windows).
- Disable the serialization import API endpoint at the reverse proxy level:
Nginx configuration to block serialization endpoint location /api/ee/serialization/import { deny all; return 403; }
3. Configure session token management to prevent misuse:
Generate a strong session token via API after authentication
curl -X POST https://metabase-instance.com/api/session \
-H "Content-Type: application/json" \
-d '{"username": "admin", "password": "your-strong-password"}'
- Implement API rate limiting to prevent brute force attacks:
Rate limiting for authentication limit_req_zone $binary_remote_addr zone=login:10m rate=5r/m;
5. Regularly audit administrative activities:
Review Metabase access logs for admin activities grep "admin" /var/log/metabase/access.log | grep "POST /api/ee/serialization/import"
- Metabase Cloud Security and Container Deployment Best Practices
Metabase Cloud instances have been confirmed vulnerable, highlighting the need for robust cloud security practices. Deployments in containerized environments such as Docker and Kubernetes require specific hardening measures. The official Metabase Docker image (metabase/metabase) should be deployed with security configurations including running as a non-root user, enabling encryption at rest for EBS volumes, and connecting through role-based access policies. All database connection details should be automatically encrypted using AES256 + SHA512 when saved, and you must set your secret key via the `MB_ENCRYPTION_SECRET_KEY` environment variable on any Pro or Enterprise plans. Crucially, to prevent unauthorized access to your application database and encrypted connection details, always run the container as an unprivileged user.
Step-by-step Docker Hardening:
- Deploy Metabase with non-root user and mounted volumes:
docker run -d -p 3000:3000 --name metabase \ --user 1000:1000 \ -v metabase-data:/metabase.db \ -e MB_ENCRYPTION_SECRET_KEY=your-256-bit-secret \ metabase/metabase:latest
2. Secure the Metabase Kubernetes deployment:
deployment.yaml with securityContext securityContext: runAsNonRoot: true runAsUser: 1000 capabilities: drop: ["ALL"]
- Implement placement in a Private Network with a reverse proxy enforcing HTTPS and automated SSL certificate renewal using Let’s Encrypt on Ubuntu with Docker Compose behind Nginx.
-
Linux and Windows System Hardening for Metabase Hosts
Beyond protecting the application itself, the underlying host system must be secured. Linux systems should run Metabase as an unprivileged user, configured as a systemd service to restrict its capabilities. Windows servers hosting Metabase should be secured with AppLocker to control allowed applications and enforce Windows Defender Firewall rules to limit inbound traffic to only the Metabase port and management IPs. Database connection details for self-hosted Pro and Enterprise plans must be encrypted, and the same applies to any stored credentials in an external application database.
Step-by-step Host Hardening:
- Create an unprivileged user to run Metabase and give the user access to app and logs. Create the `/etc/systemd/system/metabase.service` service file and open it in your editor:
Systemd service file [bash] User=metabase Group=metabase ExecStart=/usr/bin/java -jar /opt/metabase/metabase.jar
-
Set the environment variable `MB_DB_AUTOMIGRATE` to false to manually execute database updates on a staging environment.
- Set appropriate permissions on the Metabase configuration file:
sudo chmod 640 /etc/default/metabase. -
Use the Metabase CLI for administrative maintenance before deployment:
Print version and server status java -jar metabase.jar version java -jar metabase.jar status
-
Monitor cloud metadata endpoints to prevent SSRF attacks.
What Undercode Say:
Public Exploits Accelerate Attacks: The release of a working PoC script on GitHub has dramatically lowered the barrier for threat actors, who can now easily adapt it into automated campaigns targeting exposed Metabase instances. Organizations must treat this as an active, ongoing threat and prioritize patching across their entire enterprise environment.
Verified Mitigation Path Exists: While the vulnerability is severe, a clear and verified path to mitigation exists. The Metabase team has released patched versions across all affected branches, including 1.59.4, 1.58.10, and 1.57.16. For those who cannot patch immediately, a viable workaround is to block access to the serialization import endpoint, effectively neutralizing the attack vector.
Comprehensive Security Posture Required: This flaw reinforces a critical security principle: administrative accounts and vulnerable features must be protected through a defense-in-depth strategy. Organizations should reassess their Metabase deployments, ensuring that administrative interfaces are not exposed to the public internet and that network segmentation, monitoring, and the principle of least privilege are robustly enforced.
Prediction:
The public availability of this exploit will trigger a wave of automated scanning and attempted exploitation within the next 2–4 weeks. Organizations that fail to patch promptly risk data breaches, ransomware deployment, and lateral movement within their networks. This incident may also lead Metabase to accelerate architectural changes to their serialization feature, potentially implementing mandatory JWT signing for import files and deprecating H2 JDBC INIT parameter handling in future releases.
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IT/Security Reporter URL:
Reported By: Metabase Cybersecuritynews – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
