Unpatched Microsoft Exchange vulnerabilities

533 servers in Luxembourg need immediate attention

The Luxembourg House of Cybersecurity informed the CSSF of an important cyber-security alert that has been issued by CIRCL, the Computer Incident Center Luxembourg.

CIRCL published a Technical Report 72 ‘Vulnerable Microsoft Exchange server metrics leading to alarming situation’ available at the following url:

You will find here below a summary of the situation together with the corresponding recommendations in English, French and German.


Alarming situation warning – Action to be taken:

Unpatched Microsoft Exchange vulnerabilities: 533 servers in Luxembourg need immediate attention.

CIRCL identified a significant number of Microsoft Exchange servers (533 in total) that are left unmaintained when it comes to patching them with the latest security updates.

What are the risks for your organisation?

  • a potential compromise of the server
  • accessing of private, confidential and/or business related data by third parties
  • unwanted modification or deletion of data
  • exfiltration of data
  • lateral movement and infection of other parts of the infrastructure
  • financial loss through blackmailing
  • productivity and financial loss by re-installing the infrastructure
  • reputation loss

What can you do as an organisation?

  • If you’re running your own infrastructure: manually check if the currently running version is the most recent, if not, apply upgrades.
  • If you have a service provider that is supposed to take care about the security updates: ask them to report the installed version and the most recent version available. If there’s a discrepancy, insist on the upgrade. Ask for monthly status, review current contracts if necessary.

If your organisation needs support in assessing the current threat for your infrastructure, don’t hesitate to get in contact with CIRCL:

– Phone: (+352) 247 88444

– Email: GPG fingerprint: CA57 2205 C002 4E06 BA70 BE89 EAAD CFFC 22BD 4CD5

For all details, please read CIRCL’s Technical Report 72 ‘Vulnerable Microsoft Exchange server metrics leading to alarming situation’ available at the following url: