Webmail calendar sharing issue

Question

Hi there,

I am currently using Outlook Web App (OWA) through my university account, and I'm having an issue where the calendar sharing feature isn't working.

According to our university's IT department, this is a known restriction caused by a recent Microsoft Exchange Server security patch, and they said it will remain limited until Microsoft completes the update. While they suggested using the desktop app as a temporary workaround, I mostly rely on the web version for my daily work, and this breakdown is causing quite a bit of inconvenience.

Could you please let me know when this web-based calendar sharing issue is expected to be fixed? Any estimated timeline would be greatly appreciated.

Looking forward to your reply.

Best regards,

Answer 1

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Hi 최윤수

Thank you for reaching out to the Microsoft Q&A Forum. 

Based on your description, this appears to match a known issue related to CVE-2026-42897, where published calendars may not work and may return an HTTP 500 error after the mitigation is applied. 

Addressing Exchange Server May 2026 vulnerability CVE-2026-42897 | Microsoft Community Hub

 

Microsoft has since released the June 2026 Exchange Server Security Update (SU). According to the release notes, known issues introduced by the CVE-2026-42897 mitigation should be resolved once the June 2026 SU is installed and the mitigation is removed. 

Released: June 2026 Exchange Server Security Updates | Microsoft Community Hub 

I would recommend contacting your university IT department to confirm whether the June 2026 Exchange Server Security Update has already been installed in their environment. 

Best regards, 

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