Find notable cyber news and cases, enriched with sources, timelines, and signals.
Home Watchlists Beta Browse News Feed Stats About Contact

Microsoft new Outlook Excel attachment opening issue

Service Disruption
First reported
Last updated
Happening score
H score 0
1 unique sources, 1 articles

Summary

Hide ▲

The new Outlook client is experiencing a service disruption that can block users from opening Excel email attachments, interrupting routine file access. The issue has affected Exchange Online customers since at least November 23rd and is tied to an encoding error in file names. A fix has been deployed and is being validated, while users may need to use Outlook on the web or download the file locally.

Related Happenings

Microsoft Exchange Online mail flow disruption

Service Disruption
H score25 First: 02.06.2026 20:02 Last: 02.06.2026 20:02 Sources 1

About this happening: Microsoft is addressing a **widespread Exchange Online service disruption** that is delaying and failing email delivery for customers across **North America** and **Germany**. The...

Open Happening

Microsoft Teams and Office for the web file-opening outage

Service Disruption
H score25 First: 01.06.2026 17:36 Last: 01.06.2026 17:36 Sources 1

About this happening: Microsoft is investigating an ongoing **service disruption** that is blocking **Teams** and **Office for the web** users from opening files, disrupting access to shared documents...

Open Happening

Microsoft Exchange CVE-2026-42897 mitigation advisory

Advisory/Mitigation
H score44 First: 15.05.2026 12:40 Last: 15.05.2026 12:40 Sources 1

About this happening: **Microsoft** issued immediate mitigation guidance for **CVE-2026-42897**, reducing risk for **Exchange Server 2016, 2019, and Subscription Edition (SE)** on-premises servers that...

Latest development: 15.05.2026 15:35

Microsoft issued temporary mitigation guidance for CVE-2026-42897 while a patch is still in development, recommending the Exchange Emergency Mitigation (EM) Service, which is enabled by default and can be checked with the Exchange Health Checker script, or the Exchange On-premises Mitigation Tool (EOMT) for disconnected or air-gapped environments. Microsoft noted that the mitigations can disrupt features such as OWA Print Calendar and Inline images, and that servers older than March 2023 cannot receive new mitigations through EM Service.

Open Happening

Microsoft Exchange Server spoofing/XSS flaw under active exploitation (CVE-2026-42897)

Vulnerability
H score37 First: 15.05.2026 09:19 Last: 15.05.2026 09:19 Sources 1

About this happening: **CVE-2026-42897** is an **actively exploited** **spoofing** vulnerability in **on-premises Microsoft Exchange Server** that can lead to **arbitrary JavaScript execution** in a br...

Latest development: 09.06.2026 20:57

Microsoft identifies CVE-2026-42897 in Microsoft Exchange Server as an actively exploited spoofing vulnerability that can lead to JavaScript execution in a target’s browser when a specially crafted email is opened in Outlook Web Access under certain interaction conditions. Microsoft says mitigations are being pushed through the Exchange Emergency Mitigation Service while it continues work on the full update.

Open Happening

Microsoft Windows 365 Office installation disruption

Service Disruption
H score0 First: 13.05.2026 14:53 Last: 13.05.2026 14:53 Sources 1

About this happening: The **Windows 365** service update has introduced a **configuration change** that is blocking **Office downloads and installs** for some customers, disrupting access on cloud PCs....

Open Happening

Timeline

  1. 01.12.2025 19:42 1 articles · 7mo ago

    Microsoft acknowledges new Outlook Excel attachment issue

    Initial Disclosure

    Microsoft acknowledged a service issue in the new Outlook client that can prevent Exchange Online customers from opening Excel email attachments when filenames contain non-ASCII characters, and said the problem had affected customers since at least November 23rd.

    Show sources
    Open in new tab
  2. 01.12.2025 19:42 2 articles · 7mo ago

    Microsoft deploys fix for the new Outlook Excel attachment issue

    Mitigation Patch Update

    Microsoft said it has deployed a fix for the missing-encoding problem in Excel file names, is validating the deployment, and advised affected users to open the file in Outlook on the web or download it locally.

    Show sources
    Open in new tab