Microsoft Patches Record 1,413 Flaws, Including Exploited Windows Shell Bug

Microsoft on Tuesday shattered its own Patch Tuesday record by shipping patches for a whopping 1,413 vulnerabilities, including one that it said has come under active exploitation.

These include 1,102 flaws in Windows, 134 in Office, 61 in Developer Tools, 36 in SharePoint Server, and 22 in SQL Server. Of these, more than 670 relate to privilege escalation, followed by over 300 remote code execution flaws and 250 information disclosure flaws. Over 70 flaws are rated Critical in severity.

"Hundreds of CVEs in a single release used to be the exception; now it's the baseline," Dustin Childs, head of Threat Awareness at the Zero Day Initiative (ZDI), said. "Is AI to blame? Partly. It's accelerating bug-hunting on both sides of the fence, so vendors are finding (and fixing) more flaws, and researchers are finding them faster too."

"But AI isn't creating these bugs out of thin air; it's just shortening the time between a vulnerability existing and someone noticing it. The volume isn't the real story anymore. What matters is that discovery is scaling faster than exploitation, so teams that triage by sheer CVE count instead of exploitability are burning cycles on the wrong bugs. Patch what's proven, prioritized, and public, and treat everything else as this month's new normal."

The three vulnerabilities of note are listed below -

• CVE-2026-96951 (CVSS score: 8.8) - A command injection vulnerability in Windows Shell that allows an unauthorized attacker to bypass a security feature over a network.
• CVE-2026-108398 (CVSS score: 8.8) - An untrusted search path vulnerability in .NET Framework that allows an authorized attacker to bypass a security feature locally.
• CVE-2026-92707 (CVSS score: 5.3) - An improperly controlled sequential memory allocation vulnerability in MessagePack-CSharp that allows an unauthorized attacker to deny service over a network.

Microsoft, which credited Fujitsu's Riku Bamba and Yuya Chudo, as well as Anthropic's Benoit Sevens and a researcher named yhw for reporting CVE-2026-96951, said the vulnerability has been exploited in the wild.

"An attacker who successfully exploited the vulnerability could evade Mark of the Web (MOTW) defenses," the Windows-maker said. "In an email or instant message attack scenario, the attacker could send the targeted user a specially crafted file that is designed to exploit the vulnerability."

"In any case an attacker would have no way to force a user to view attacker-controlled content. Instead, an attacker would have to convince a user to take action. For example, an attacker could entice a user to either click a link that directs the user to the attacker's site or send a malicious attachment."

It's unclear how the vulnerability is being exploited in real-world attacks, by whom, and who has been targeted. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added the flaw to its Known Exploited Vulnerabilities (KEV) catalog, requiring federal agencies to apply the fixes by October 16, 2026.

CVE-2026-108398 has been acknowledged as publicly known at the time of the release of the patches, with Microsoft stating the security flaw could be exploited to bypass Windows Defender Application Control (WDAC) enforcement and run unauthorized applications on target systems.

"An authenticated attacker could place a specially crafted .NET assembly on an affected system and register it for loading by a protected process," Microsoft said. "Successful exploitation could bypass Windows Defender Application Control restrictions and allow the attacker to execute code within the protected process. User interaction is not required."

"This vulnerability is particularly dangerous as a post-compromise attack technique, enabling attackers with existing local access to circumvent security restrictions without user interaction," Mike Walters, president and co-founder of Action1, said. "Successful exploitation could compromise system integrity, expose sensitive business information, weaken endpoint defenses, and disrupt critical operations."

Microsoft attributed the vulnerability discovery to James Forshaw with Google Project Zero, while crediting an anonymous researcher for reporting CVE-2026-92707. The security flaw is the second to be tagged as publicly disclosed.

Patches have also been released for a non-Microsoft CVE (CVE-2026-21413, CVSS score: 9.8), a heap-based buffer overflow impacting Raw Image Extension that could result in remote code execution.

"An attacker could exploit this vulnerability by convincing a user to navigate to a folder containing a specially crafted RAW image file," Microsoft said. "The vulnerability can be triggered when Windows generates a thumbnail or preview; the user does not need to open the file."

The development comes amid continued use of artificial intelligence (AI)-assisted approaches to discover and remediate security vulnerabilities. Last month, Microsoft addressed nearly 1,000 vulnerabilities. According to Satnam Narang, senior staff research engineer at Tenable, more than 4,000 CVEs have been patched by Microsoft this year alone.

"The sheer volume of vulnerabilities in recent Patch Tuesday releases can easily include several examples of potentially concerning vulnerabilities, each of which might have been more remarkable in its own right back when volumes were lower," Adam Barnett, Lead Software Engineer at Rapid7, said.

Along with this month's updates, Redmond has also introduced a new method to help organizations prioritize security updates by grouping related flaws into what it calls "risk cohorts."

"A risk cohort is a group of CVEs that require a similar customer assessment," Microsoft said. "Risk cohorts are a starting point, not a final decision. Customers should continue to review each CVE for active exploitation, severity, attack vector, user interaction, and product-specific guidance."

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