How much harm can access to a printer or a print management system inside a LAN cause when exploited by a malicious actor?

At first glance, probably not much. After all, printing infrastructure is rarely the first thing that comes to mind when thinking about critical systems. But things can change quickly when configuration mistakes accumulate and a seemingly non-critical system is integrated with other parts of the environment.

Here is a real-life example from one of my penetration tests.

During an assessment, I discovered a print management system accessible within the LAN using default credentials. A simple and, unfortunately, still common configuration mistake.

On its own, unauthorized access to a print management system might not seem particularly serious. In this case, however, the system was not isolated. It was integrated with several external services, including:

• SMTP for sending emails,

• FTP for storing and delivering scans,

• Active Directory (LDAP) for importing the user address book,

• SharePoint for file storage.

This made the system much more interesting from an attacker's perspective.
From a misconfiguration to a vulnerability The application had only a single administrator account configured. While inspecting the integration settings, I noticed something more important: credentials that had already been configured for external services were returned to the browser in plaintext and could be recovered directly from the HTML source of the administration pages.

In other words, an authenticated administrator could retrieve passwords that the system used to communicate with SMTP, FTP, Active Directory or SharePoint.

This distinction is important.

The use of default credentials was a configuration issue specific to the tested environment. CVE-2026-15933 was a vulnerability in the product itself. The first issue provided administrative access to the application; the second made that access potentially much more valuable.

As long as only a legitimate administrator can access the application, the problem may remain unnoticed. Once an unauthorized user obtains administrative access, the situation changes significantly.

Instead of compromising only a print management system, an attacker also obtains credentials to connected services.

What happens next depends on the permissions assigned to those accounts. They might provide only limited access, or they might expose additional systems, files or functionality and create an opportunity for further lateral movement inside the environment.

A system does not have to be business-critical itself to become an important part of an attack path. Sometimes what matters more is what the system is trusted to access.
Timeline
• 08.07.2026 – Vulnerability reported to CERT Polska

• 14.07.2026 – Vulnerability confirmed by the vendor

• 03.09.2026 – Public notification published at https://cert.pl/en/posts/2026/09/CVE-2026-15933/
The broader lesson Technically, this was not a sophisticated vulnerability. There was no complex exploit chain, memory corruption or remote code execution.

But that is also what makes this example useful and shows importance of in-depth defence. Single layer of defence – access protection to the system – can fail, but secure product, following best practices can limit the damage.

Real-world compromises do not always begin with critical vulnerabilities. An attacker may start with something as ordinary as a forgotten system using default credentials. If that system stores credentials to other services, one minor „weakness” can become a stepping stone to much more valuable assets.

This is also why penetration testing should not end with identifying an individual vulnerability or misconfiguration. The important question is often: