Microsoft’s October Patch Tuesday release addresses a record-breaking 1,413 vulnerabilities, including an actively exploited Windows Shell zero-day and two other publicly disclosed flaws.

Just when you thought a previous record would stand for a while, Microsoft comes out again with the largest monthly Patch Tuesday release. Microsoft has said its growing use of AI to find and fix security vulnerabilities means users should expect more fixes in its monthly updates.

How to apply patches and check if you’re protected

These updates fix security problems and help keep your Windows PC protected. Here’s how to make sure you’re up to date:

• Click the Start button, then open Settings.
• Select Windows Update (usually at the bottom of the menu on the left).
• Click Check for updates. Windows will search for the latest security updates. If you’ve enabled Get the latest updates as soon as they’re available under More options, you may be prompted to restart immediately to complete the update.
  
• Otherwise, continue to the next step.
• If updates are available, they’ll start downloading automatically. When they’re ready, click Install or Restart now if prompted. Your computer may need a restart to finish the update.
• After restarting, go back to Windows Update and check again. If it says You’re up to date, you’re all set.

Technical details

As usual, we’ve selected a few vulnerabilities to highlight for readers interested in the technical details.

We’ll start with the actively exploited vulnerability tracked as CVE-2026-96951 (CVSS score 8.8 out of 10), a Windows Shell security feature bypass vulnerability.

The security feature it can bypass is the Mark of the Web (MOTW) defense, which can warn users about potentially unsafe downloaded files.

Successful exploitation requires user interaction. For example, in an email or instant message attack, the attacker could send the targeted user a specially crafted file designed to exploit the vulnerability, but the user would have to click a link or open an attachment.

Another one to keep an eye on is CVE-2026-108398 (CVSS score 8.8 out of 10), where an untrusted search path in .NET Framework allows an authorized attacker to bypass a security feature locally. The bypassed feature is Windows Defender Application Control (WDAC), which could lead to the ability to run unauthorized applications on target systems. This vulnerability was publicly disclosed before the patch.

Another publicly disclosed vulnerability is CVE-2026-92707 (CVSS score 5.3 out of 10). The flaw can let an unauthenticated remote attacker exhaust memory in affected applications that process specially crafted MessagePack data. MessagePack-CSharp is a software component that helps applications pack and unpack data in a compact format, making it efficient to store or exchange information. Exposure depends on how a service uses the library to pack and unpack the information.

From reporting threats to removing them.

Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today.

Microsoft’s September 2026 Patch Tuesday addresses 964 CVEs, including 104 rated Critical and 860 rated Important, making it the company’s largest Patch Tuesday release on record.

Microsoft lists 974 CVEs in its full September security release. However, 10 of those affect cloud services or involve fixes that Microsoft applies itself, leaving 964 vulnerabilities that customers need to patch.

The release includes fixes for two actively exploited Windows zero-days. Both are local elevation-of-privilege vulnerabilities that could allow an attacker who already has access to a device to gain SYSTEM privileges. Neither provides remote access by itself, but SYSTEM-level access is valuable to malware operators after they gain an initial foothold through phishing, stolen credentials, or another method.

How to apply patches and check if you’re protected

These updates fix security problems and help keep your Windows PC protected. Here’s how to make sure you’re up to date:

• Click the Start button, then open Settings.
• Select Windows Update (usually at the bottom of the menu on the left).
• Click Check for updates. Windows will search for the latest security updates. If you’ve enabled Get the latest updates as soon as they’re available under More options, you may be prompted to restart immediately to complete the update. Otherwise, continue to the next step.

• If updates are available, they’ll start downloading automatically. When they’re ready, click Install or Restart now if prompted. Your computer may need a restart to finish the update.
• After restarting, go back to Windows Update and check again. If it says You’re up to date, you’re all set.
  

Technical details

The unusually large batch also includes high-severity remote-code-execution vulnerabilities in Windows DNS Server and Remote Desktop Services, as well as fixes affecting Exchange Server, SharePoint, SQL Server, Office, and core Windows components.

Let’s take a closer look at the two zero-day vulnerabilities. Microsoft classifies a vulnerability as a zero-day if it was publicly disclosed or actively exploited before an official fix became available.

The first is a Windows Update Stack elevation-of-privilege (EoP) vulnerability with a CVSS score of 7.8 out of 10, tracked as CVE-2026-81963. The description says:

“Improper link resolution before file access (‘link following’) in Windows Update Stack allows an authorized attacker to elevate privileges locally.”

This means Windows can be persuaded to open or modify the wrong file because it follows a shortcut-like pointer without properly checking where that pointer leads. Microsoft says attackers exploited the bug before a patch was available.

The second zero-day, tracked as CVE-2026-85880, also has a CVSS score of 7.8 out of 10. Microsoft describes it as:

“heap-based buffer overflow in Windows ALPC allows an authorized attacker to elevate privileges locally.”

Microsoft says an attacker who can execute code in a low-privilege AppContainer could exploit the vulnerability locally to escape the sandbox and elevate their privileges on the affected system. No additional user interaction is required.

Windows ALPC is an internal messaging system in the Windows operating system that allows different programs on the same computer to communicate with each other quickly.

A buffer overflow occurs when an area of memory within a software application reaches its boundary and data spills into an adjacent memory region. The heap is a region of memory used for dynamic memory allocation.

These are not the kinds of bugs a typical victim triggers merely by opening a malicious document or visiting a website. But local privilege escalation is a critical part of many attack chains: After malware runs with limited rights, a SYSTEM-level exploit can help an intruder disable defenses, access protected data, establish persistence, or move through a network.

From reporting threats to removing them.

Cybersecurity risks should never spread beyond a headline. Keep threats off your devices by downloading Malwarebytes today.

Microsoft’s August 2026 Patch Tuesday addresses 421 Microsoft vulnerabilities, including 62 rated Critical. One Windows vulnerability has been exploited in the wild by the Lazarus group to gain SYSTEM privileges.

The August update is smaller than July’s record-breaking release, but it’s still among Microsoft’s largest Patch Tuesday batches. More importantly, it includes several flaws likely to attract attacker interest: a publicly disclosed Windows privilege escalation flaw with a proof-of-concept (PoC), a newly completed unauthenticated SharePoint remote code execution (RCE) chain, and a potentially wormable Windows DNS Server flaw.

How to apply patches and check if you’re protected

These updates fix security problems and help keep your Windows PC protected. Here’s how to make sure you’re up to date:

• Click the Start button, then open Settings.
• Select Windows Update (usually at the bottom of the menu on the left).
• Click Check for updates. Windows will search for the latest security updates. If you’ve enabled Get the latest updates as soon as they’re available under More options, you may be prompted to restart immediately to complete the update. Otherwise, continue to the next step.

• If updates are available, they’ll start downloading automatically. When they’re ready, click Install or Restart now if prompted. Your computer may need a restart to finish the update.
• After restarting, go back to Windows Update and check again. If it says You’re up to date, you’re all set.

Technical details

Windows Deployment Services (WDS) users should prioritize CVE-2026-62893 (CVSS score 9.8 out of 10), an unauthenticated RCE flaw in the TFTP (Trivial File Transfer Protocol) server. TFTP normally runs on UDP port 69 and has no built-in authentication. It is primarily an enterprise and school network issue, but it could enable lateral movement where WDS is deployed.

Microsoft also fixed CVE-2026-62832, a publicly disclosed elevation of privilege (EoP) vulnerability in the Windows User Profile Service. It maps to the issue researchers called LegacyHive, for which a limited public proof of concept was released in July.

The PoC demonstrates how a local authenticated attacker could abuse the service’s registry hive handling to load another user’s hive, potentially including an administrator’s. The released demonstration is deliberately constrained and requires credentials for another user, but the availability of code and the broad Windows footprint make this one a strong candidate for exploitation attempts.

Another good reason to promptly update is the number (I counted 48) of remote code execution (RCE) fixes for Office applications and components, including Excel, Word, Outlook, PowerPoint, and the Office graphics component. Document-borne vulnerabilities are attractive to phishing operators because email attachments and shared documents provide delivery mechanisms that people are likely to open.

“One of the best cybersecurity suites on the planet.” 

According to CNET. Read their review →

Just one month ago, June 2026 Patch Tuesday broke Microsoft’s previous record with 206 CVEs and three zero‑days. July now triples that count, reinforcing that the era of “small” Patch Tuesdays may be over as AI‑driven vulnerability discovery ramps up.

The update includes 59 critical vulnerabilities, as well as three publicly disclosed zero-days. Microsoft classifies these as zero-days because information about the vulnerabilities became public before patches were available. Two are known to be actively exploited by attackers.

How to apply patches and check if you’re protected

These updates fix security problems and keep your Windows PC protected. Here’s how to make sure you’re up to date:

1. Open Settings

• Click the Start button, then open Settings.

2. Go to Windows Update

• Select Windows Update (usually at the bottom of the menu on the left).

3. Check for updates

• Click Check for updates. Windows will search for the latest security updates.
• If you’ve enabled Get the latest updates as soon as they’re available under More options, you may be prompted to restart immediately. If so, restart your computer to complete the update. Otherwise, continue to the next step.
  

4. Download and install

• If updates are available, they’ll start downloading automatically. When they’re ready, click Install or Restart now if prompted. Your computer may need a restart to finish the update.

5. Double-check you’re up to date

• After restarting, go back to Windows Update and check again. If it says You’re up to date, you’re all set.

Technical details

Let’s look at the three zero-days.

First is a Windows BitLocker security feature bypass vulnerability, tracked as CVE-2026-50661. It is not known to be actively exploited. Microsoft describes it as:

“Protection mechanism failure in Windows BitLocker allows an unauthorized attacker to bypass a security feature with a physical attack.”

In other words, even if you’ve encrypted your machine with BitLocker, an attacker could exploit this vulnerability to access your data if they have physical access to your computer.

Next is the actively exploited CVE-2026-56155, an Active Directory Federation Services (ADFS) elevation of privilege (EoP) vulnerability. ADFS is a Microsoft software component that provides single sign-on (SSO) and federated access. It acts as a trust broker between an organization’s Active Directory and applications. An attacker who successfully exploited this vulnerability could gain administrator privileges. Reportedly, Microsoft discovered the vulnerability while investigating active attacks.

Last but not least is CVE-2026-56164, a Microsoft SharePoint Server elevation of privilege vulnerability. SharePoint Server is the on-premises version of Microsoft’s web-based collaboration and document management platform. A missing authentication check in Microsoft Office SharePoint could allow an attacker to elevate privileges over a network.

Both actively exploited vulnerabilities have been added to the Cybersecurity and Infrastructure Security Agency (CISA) Known Exploited Vulnerabilities (KEV) Catalog, which sets patch deadlines for Federal Civilian Executive Branch (FCEB) agencies. CISA has also urged organizations using SharePoint Server to implement hardening measures after the latest exploitations.

“One of the best cybersecurity suites on the planet.” 

According to CNET. Read their review →