Microsoft April 2026 Patch Tuesday fixes 167 vulnerabilities and two zero-days

Microsoft released its April 2026 Patch Tuesday update on April 14, 2026, which addresses more than 160 security vulnerabilities, including two zero-day flaws, one of which was reported as actively exploited before patches became available.

The monthly rollout includes cumulative updates for supported Windows versions. Windows 11 versions 25H2 and 24H2 receive KB5083769, while Windows 11 version 23H2 receives KB5082052. These updates install automatically on most consumer devices unless Windows Update has been paused.

Security researchers described the April release as larger than average, with a higher-than-usual number of fixes affecting core Windows components.

Vulnerability totals vary across security vendors

Different security vendors reported slightly different vulnerability counts for April.

Microsoft addressed 167 vulnerabilities, including one actively exploited zero-day and one publicly disclosed vulnerability before release. Other security firms, including Qualys, reported totals closer to 163 to 164 vulnerabilities, with eight rated Critical.

Despite minor differences in counting methods, researchers broadly agree that April’s update cycle includes:

• Two zero-day vulnerabilities
• Eight Critical-severity flaws
• A large number of elevation-of-privilege vulnerabilities, which formed the largest category in several reports

Zero-day vulnerabilities typically increase urgency because they may already be known to attackers before patches are released.

Windows 11 KB5083769 introduces new builds and reliability fixes

Microsoft’s primary Windows 11 update for April is KB5083769, which updates systems to new builds after installation:

• Windows 11 version 25H2: Build 26200.8246
• Windows 11 version 24H2: Build 26100.8246

In addition to security fixes, the update includes reliability improvements and ongoing security hardening changes. Microsoft also introduced protections related to Remote Desktop usage, including warnings when opening unfamiliar .rdp configuration files.

These changes are part of Microsoft’s broader effort to reduce credential theft and phishing attacks that rely on remote connection tools.

Additional updates released for older Windows versions

Microsoft also published security updates for earlier Windows versions as part of the April cycle. Windows 11 version 23H2 received KB5082052, while supported Windows 10 systems received their own cumulative security updates.

Microsoft classifies these updates as mandatory because they address security vulnerabilities discovered in recent months. Systems configured for automatic updates will typically install them without user action.