Microsoft today issued updates to fix more than 1,400 security vulnerabilities in its Windows operating systems and other software. Today’s epic patch batch dwarfs September’s record of nearly 1,000 fixes, which was already about ten times the normal monthly patch load from Redmond.

Just one of the weaknesses patched this week is considered a “zero day,” or already exploited in the wild. CVE-2026-96951 is a security feature bypass in the Windows Shell that affects Windows 10 and 11 systems, as well as some Server versions.

Windows 10 users might be wondering if they can still expect security updates after this month. Microsoft had been slated to stop shipping updates for Windows 10 systems in October 2025, but ended up adding another year of free updates after considerable pushback. A few months ago, Microsoft quietly extended that support for another year (until October 2027).

At least 78 of the flaws fixed this month are rated “critical,” meaning they could be exploited with little or no action by the user, and most of those critical bugs allow an attacker to execute code of their choice on the vulnerable system.

While Microsoft said there are no signs anyone is exploiting it yet, a security feature bypass in the .NET Framework (CVE-2026-108398) was publicly disclosed prior to today, potentially giving attackers advance time to work out how to exploit the bug.

Satnam Narang at Tenable said the number of flaws fixed this month far surpasses the previous record-setting year 2020, when Microsoft patched 1,261 CVEs.

“We’ve now crossed the 4,000 CVE mark with two months left to go,” he said.

Microsoft credits large language models for the high volume of bug discovery, and presumably AI gets credit for many of the patches used to fix these flaw. Meanwhile, security experts have been warning that these unusually large patch volleys from Microsoft are placing extra strain on corporate security teams, which often have to test individual updates before deploying them across a network to ensure the fixes don’t cause problems for other software.

Tyler Reguly, associate director of security research and development at Fortra, notes that just 26 Microsoft vulnerabilities appeared in the “Known Exploited Vulnerabilities” (KEV) catalog maintained by the U.S. Cybersecurity & Infrastructure Security Agency (CISA) so far this year, and security teams would do well to prioritize patching those 26 vulnerabilities first.

“Security leaders should focus on exploitable risk, and ask whether their teams have the clarity, capacity and support to act,” Reguly said.

Which vulnerabilities deserve the most scrutiny in your organization? The folks at Cisco Talos have a useful roundup of the more noteworthy flaws that Microsoft fixed today, and of course the SANS Internet Storm Center has a reliable roundup that indexes vulnerabilities by severity, CVE number and affected software.

Microsoft today released updates to fix more than 50 security holes in its Windows operating systems and other software, including patches for a whopping six “zero-day” vulnerabilities that attackers are already exploiting in the wild.

Zero-day #1 this month is CVE-2026-21510, a security feature bypass vulnerability in Windows Shell wherein a single click on a malicious link can quietly bypass Windows protections and run attacker-controlled content without warning or consent dialogs. CVE-2026-21510 affects all currently supported versions of Windows.

The zero-day flaw CVE-2026-21513 is a security bypass bug targeting MSHTML, the proprietary engine of the default Web browser in Windows. CVE-2026-21514 is a related security feature bypass in Microsoft Word.

The zero-day CVE-2026-21533 allows local attackers to elevate their user privileges to “SYSTEM” level access in Windows Remote Desktop Services. CVE-2026-21519 is a zero-day elevation of privilege flaw in the Desktop Window Manager (DWM), a key component of Windows that organizes windows on a user’s screen. Microsoft fixed a different zero-day in DWM just last month.

The sixth zero-day is CVE-2026-21525, a potentially disruptive denial-of-service vulnerability in the Windows Remote Access Connection Manager, the service responsible for maintaining VPN connections to corporate networks.

Chris Goettl at Ivanti reminds us Microsoft has issued several out-of-band security updates since January’s Patch Tuesday. On January 17, Microsoft pushed a fix that resolved a credential prompt failure when attempting remote desktop or remote application connections. On January 26, Microsoft patched a zero-day security feature bypass vulnerability (CVE-2026-21509) in Microsoft Office.

Kev Breen at Immersive notes that this month’s Patch Tuesday includes several fixes for remote code execution vulnerabilities affecting GitHub Copilot and multiple integrated development environments (IDEs), including VS Code, Visual Studio, and JetBrains products. The relevant CVEs are CVE-2026-21516, CVE-2026-21523, and CVE-2026-21256.

Breen said the AI vulnerabilities Microsoft patched this month stem from a command injection flaw that can be triggered through prompt injection, or tricking the AI agent into doing something it shouldn’t — like executing malicious code or commands.

“Developers are high-value targets for threat actors, as they often have access to sensitive data such as API keys and secrets that function as keys to critical infrastructure, including privileged AWS or Azure API keys,” Breen said. “When organizations enable developers and automation pipelines to use LLMs and agentic AI, a malicious prompt can have significant impact. This does not mean organizations should stop using AI. It does mean developers should understand the risks, teams should clearly identify which systems and workflows have access to AI agents, and least-privilege principles should be applied to limit the blast radius if developer secrets are compromised.”

The SANS Internet Storm Center has a clickable breakdown of each individual fix this month from Microsoft, indexed by severity and CVSS score. Enterprise Windows admins involved in testing patches before rolling them out should keep an eye on askwoody.com, which often has the skinny on wonky updates. Please don’t neglect to back up your data if it has been a while since you’ve done that, and feel free to sound off in the comments if you experience problems installing any of these fixes.