A security incident recently occurred involving VOSviewer,a software tool developed by CWTS and used by researchers worldwide. The incident was detected quickly, and immediate measures were taken to limit any potential impact. The Security Operations Centre (SOC) is investigating the incident in collaboration with specialised partners. Currently, there are no indications of a broad impact within the university or the wider international academic and research community. The situation is under control, and any potentially affected users are being contacted proactively. In case of any questions, please contact abuse@issc.leidenuniv.nl.

There is a glitch causing visitors to unintentionally see a CAPTCHA in some cases. We are investigating this as a priority. We apologize for the inconvenience.

Leiden University is moving to a more uniform sign-in experience. As a result, the familiar blue ULCN sign-in page will gradually be replaced by the Microsoft sign-in screen, which is already used for many university services. This change means you will need to sign in less often across different systems and services. By using Single Sign-On (SSO), you will typically only need to sign in once, as long as you continue working in the same web browser.

This morning there was a brief disruption affecting the new login page; all issues have now been resolved. For more information, see: https://www.staff.universiteitleiden.nl/announcements/2026/08/a-new-look-for-the-ulcn-login-screen?cf=service-units&cd=administration-and-central-services If you are still experiencing problems, please contact the ISSC Helpdesk. 071-527 8888

At the moment, there is an outage affecting eduroam across Leiden University. This means you are currently unable to log in via Wi‑Fi. We are analysing the problem and are working with priority on a solution. Until then, you can: use a mobile hotspot via your phone to get internet access; work from home if that is a suitable option for your work.

There is currently an issue with signing in using multi-factor authentication via email. The emails with the verification code are arriving late. In some cases, the code arrives so late that it no longer works, or the email does not arrive at all. For a workaround to sign in using another multi-factor authentication method, please contact the helpdesk.

At the moment, we are experiencing an outage, which means our incident registration system is not available.

The USIS website is currently unavailable. We are working on a solution and doing our best to restore the service as quickly as possible.

Due to a technical fault, the Leiden University staff website is currently unavailable.

Videos from Mediasite are currently not functioning. The supplier has identified the issue and is actively working on a solution.