Feb 2026: Microsoft Outlook Spoofing Vulnerability
CVE-2026-21511 Published on February 10, 2026
Microsoft Outlook Spoofing Vulnerability
Deserialization of untrusted data in Microsoft Office Outlook allows an unauthorized attacker to perform spoofing over a network.
Weakness Type
What is a Marshaling, Unmarshaling Vulnerability?
The application deserializes untrusted data without sufficiently verifying that the resulting data will be valid.
CVE-2026-21511 has been classified to as a Marshaling, Unmarshaling vulnerability or weakness.
Products Associated with CVE-2026-21511
Want to know whenever a new CVE is published for Microsoft products? stack.watch will email you.
Affected Versions
Microsoft 365 Apps for Enterprise:- Version 16.0.1 and below https://aka.ms/OfficeSecurityReleases is affected.
- Version 19.0.0 and below https://aka.ms/OfficeSecurityReleases is affected.
- Version 16.0.1 and below https://aka.ms/OfficeSecurityReleases is affected.
- Version 16.0.0 and below https://aka.ms/OfficeSecurityReleases is affected.
- Version 16.0.1 and below 16.106.26020821 is affected.
- Version 16.0.0 and below 16.106.26020821 is affected.
- Version 16.0.0 and below 16.0.5539.1002 is affected.
- Version 16.0.0 and below 16.0.10417.20097 is affected.
- Version 16.0.0 and below 16.0.19127.20518 is affected.
- Version 16.0.1 and below 16.0.5539.1002 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.