CVE-2026-124194 is a medium-severity vulnerability. Product UI does not warn the user of unsafe actions in Microsoft Office Outlook, allowing an unauthorized attacker to perform spoofing over a network.

This vulnerability affects Microsoft Office Outlook in the following products and versions:

Microsoft 365 Apps for Enterprise versions prior to the latest security release – (Affected)
Microsoft Office LTSC 2021 versions earlier than 16.0.14334.21048 – (Affected)
Microsoft Office LTSC 2024 versions earlier than 16.0.17932.21140 – (Affected)

CVE-2026-124194 is a spoofing vulnerability caused by insufficient warning of unsafe actions within Microsoft Office Outlook. An attacker can trick a user into trusting malicious content, potentially exposing sensitive information.

Step 1 - Prepare a Malicious Email or Link

The attacker creates a specially crafted email, link, or content designed to appear legitimate to the target user.

Step 2 - Deliver the Content to the Victim

The attacker sends the malicious content through email or another network-based communication channel.

Step 3 - User Interacts with the Content

The victim opens or interacts with the malicious content. User interaction is required for successful exploitation.

Step 4 - Spoofing Occurs

Due to inadequate warnings for unsafe actions, Outlook may allow the attacker to impersonate a trusted source or present misleading content, potentially exposing sensitive information.

CERTVU recommends the following:

1. Upgrade Immediately

   Update affected Microsoft 365 Apps for Enterprise, Microsoft Office LTSC 2021, and Microsoft Office LTSC 2024 to the latest supported versions.

2. Exercise Caution with Emails

   Avoid opening unexpected attachments, clicking unknown links, or interacting with suspicious email content.

3. Enable Security Awareness Training

   Educate users on identifying phishing attempts, spoofed emails, and fraudulent links.

4. Monitor for Indicators of Compromise

   Review email security logs, suspicious message activity, and reports of unusual Outlook behaviour.

5. Implement Email Security Controls

   Use spam filtering, anti-phishing protections, and email authentication technologies such as SPF, DKIM, and DMARC to reduce spoofing risks.