CVE-2026-21511: high-severity vulnerability in Microsoft 365 Apps for Enterprise
Microsoft Outlook Spoofing Vulnerability
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 4.0%
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C
Affected products
Microsoft · Microsoft 365 Apps for EnterpriseMicrosoft · Microsoft Office 2019Microsoft · Microsoft Office LTSC 2021Microsoft · Microsoft Office LTSC 2024Microsoft · Microsoft Office LTSC for Mac 2021Microsoft · Microsoft Office LTSC for Mac 2024Microsoft · Microsoft SharePoint Enterprise Server 2016Microsoft · Microsoft SharePoint Server 2019Microsoft · Microsoft SharePoint Server Subscription EditionMicrosoft · Microsoft Word 2016Related CVEs — Microsoft 365 Apps for Enterprise
In the same product, most dangerous first.
CVE-2023-23397CRITICALMicrosoft Outlook Elevation of Privilege VulnerabilityEPSS 97.2%KEVCVE-2024-21413CRITICALMicrosoft Outlook Remote Code Execution VulnerabilityEPSS 94.7%KEVCVE-2026-21509HIGHMicrosoft Office Security Feature Bypass VulnerabilityEPSS 70.8%KEVCVE-2021-42292HIGHMicrosoft Excel Security Feature Bypass VulnerabilityEPSS 43.0%KEVCVE-2023-36761MEDIUMMicrosoft Word Information Disclosure VulnerabilityEPSS 19.6%KEVCVE-2023-35311HIGHMicrosoft Outlook Security Feature Bypass VulnerabilityEPSS 15.5%KEV