MongoBleed: When Negligence Becomes a Security Flaw

Germany in Third Place – But Not in Patching

Shortly before the end of 2025, what had long been practice became known: Over 11,500 MongoDB instances in Germany are freely accessible via the internet and vulnerable to a critical security flaw known as MongoBleed. Globally, Germany thus occupies a sad third place – right behind China and the USA. Particularly piquant: No hoster worldwide counts more vulnerable instances than Hetzner, a German provider.

What might at first glance appear like another chapter in the endless series of CVEs is in truth a structural problem: it’s not about the bug in the code, but about organizational failure in the operation of digital infrastructures – across providers, customers, and areas of responsibility.

What is MongoBleed?

MongoBleed refers to the security vulnerability CVE-2025-14847 with a CVSS score of 8.7 (high). It affects MongoDB instances where zlib compression is enabled – a configuration feature that, according to security researchers, is frequently set by default.

The flaw allows attackers to access sensitive data such as credentials or contents of productive databases via the network without authentication. Public exploit code is already available, and the number of potential attacks is increasing daily.

Worldwide, according to Shodan, about 90,000 MongoDB instances are affected. Germany ranks third with 11,547 vulnerable instances – and among providers, Hetzner stands out with over 6,800 exposed systems.

MongoDB: Flexible, Popular – But Not a Surefire Success

MongoDB is a document-oriented NoSQL database that is particularly well-suited for modern web and big data applications. It is scalable, schemaless, fast, and popular with developer teams for its flexibility in handling complex and unstructured data.

But precisely this flexibility also brings responsibility. MongoDB is not a plug-and-play product with a security guarantee, but demands conscious and professional operation – especially if instances are publicly reachable or contain productive data.

Cloud is Not a Security Promise – It is an Operating Model

Particularly explosive: The majority of vulnerable instances run with well-known IaaS providers like Hetzner, Alibaba, or Google Cloud. This again shows a dangerous misconception:

“Because it runs in the cloud, it is secure.”

The opposite is the case. Responsibility merely shifts – it doesn’t disappear. Cloud providers provide resources, but the security of applications, configurations, and data remains the user’s responsibility.

That Hetzner is at the top of vulnerable systems does not necessarily mean misconduct by the provider – but it shows how inadequate the transparency, control, and security practice in the use of IaaS infrastructure still is. The cloud becomes a security risk when security standards are not systematically demanded and checked.

The Actual Problem: Months of Inaction

The vulnerability is not new. The exploit is public, the patches are ready, countermeasures are known. And yet, tens of thousands of instances remain unpatched, insecure, and openly accessible. This is not a technical but an organizational problem – a system failure in IT operations.

We see a pattern here that has been repeating for years:

1. A critical gap is discovered.
2. Security researchers publish the exploit.
3. Media report, IT departments react slowly or not at all.
4. Attackers systematically exploit the vulnerability.

That was the case with CitrixBleed, with Log4Shell, with Exchange – and now with MongoBleed.

Digital Sovereignty Begins with Responsibility

Germany discusses digital sovereignty, open source promotion, and strategic dependencies. But this discussion remains academic when simultaneously thousands of productive databases are unpatched on the net – with critical vulnerabilities that are ignored for weeks.

Open source is not the problem. On the contrary: MongoDB delivered patches promptly – transparently, documented, traceably. The risk arises where operation, maintenance, and security are outsourced cheaply, without binding standards, without monitoring, without responsibility.

What to Do Now – Recommendations for Operators

Whether startup, medium-sized business, or corporation – anyone operating MongoDB or other productive services should act now:

1. Check Security Status:
   • Is zlib compression enabled?
   • Is the instance publicly accessible?
   • Is a vulnerable version running?
2. Take Immediate Measures:
   • Patch to current versions
   • If not possible in the short term: disable zlib, secure port 27017 internally (e.g., via VPN or firewall)
3. Clarify Responsibilities:
   • Who is responsible for security monitoring?
   • Are there automated patch processes?
   • Are open ports and services regularly checked?
4. Long-term Lessons:
   • Security checks are part of the deployment standard.
   • Cloud use needs security policies, not “fire and forget”.
   • Security updates are an operational duty, not a “nice to have”.

Conclusion: Security is a Question of Attitude

MongoBleed is not an isolated case. It is a symptom of a structural lack of security culture in the operation of digital systems. Not MongoDB is insecure – what is insecure is how it is handled.

In a time when data is the foundation of economic and state processes, security must no longer be shifted to the last mile in the DevOps process. Those who operate systems bear responsibility. Those who use the cloud need competence. And those who host critical infrastructure must not hide behind the customer.

Security is not a function of the software – but of the organization behind it.