Microsoft’s March Patch Tuesday security release shipped fixes for 83 vulnerabilities across its enterprise software and services, and was notable for having no actively exploited zero-days for the first time in six months. Microsoft flagged six vulnerabilities as “more likely to be exploited,” and noted two issues—CVE-2026-21262 and CVE-2026-26127—were publicly known at release. Researchers highlighted an Excel information-disclosure issue, CVE-2026-26144, describing a scenario where an attacker could potentially induce a Copilot Agent to exfiltrate data in a zero-click style workflow, and also pointed to Office flaws CVE-2026-26110 and CVE-2026-26113 (CVSS 8.4) that could enable arbitrary code execution via the Office preview pane.
Microsoft also released mandatory Windows 11 cumulative updates KB5079473 (25H2/24H2) and KB5078883 (23H2) that incorporate the March 2026 Patch Tuesday security fixes, along with additional non-security changes. The updates advance build numbers to 26200.8037/26100.8037 (25H2/24H2) and 22631.6783 (23H2), expand “high-confidence device targeting” to increase coverage for automatic delivery of new Secure Boot certificates, and include reliability improvements such as better File Explorer search across drives and changes to Windows Defender Application Control (WDAC) behavior for COM objects (policy listing support).

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On 2026-03-11, JPCERT/CC published advisory JPCERT-AT-2026-0005 warning that vulnerabilities fixed in Microsoft's March 2026 updates could allow remote code execution. It urged organizations to review Microsoft's guidance and apply the relevant updates through Microsoft Update, Windows Update, or the Update Catalog.
In connection with the March 2026 Patch Tuesday cycle, Microsoft said Windows Autopatch defaults would change to enable hotpatch security updates for eligible devices starting with the May 2026 Windows security update. This signaled an upcoming change in how some enterprise systems will receive security fixes.
On 2026-03-10, Microsoft released mandatory Windows 11 cumulative updates KB5079473 for versions 25H2/24H2 and KB5078883 for version 23H2. The updates addressed security issues and bugs, expanded Secure Boot certificate targeting, and added features including built-in Sysmon as an optional native Windows feature.
Microsoft included CVE-2026-21536, a critical remote code execution flaw in the Microsoft Devices Pricing Program, in the March 2026 disclosures and stated the issue had already been fully mitigated server-side. Multiple reports noted that no customer action was required for this specific vulnerability.
Microsoft fixed critical Office remote code execution vulnerabilities CVE-2026-26110 and CVE-2026-26113, which can be triggered through the Office Preview Pane, as well as Excel information disclosure flaw CVE-2026-26144. Researchers noted the Excel issue could enable zero-click style data exfiltration through Microsoft 365 Copilot Agent mode.
The March 2026 release patched CVE-2026-21262, a SQL Server privilege-escalation flaw that could let an authorized user gain sysadmin privileges, and CVE-2026-26127, a .NET denial-of-service bug. Both issues were publicly known before patches were released, but Microsoft reported no evidence of in-the-wild exploitation.
On 2026-03-10, Microsoft issued its March 2026 Patch Tuesday updates, fixing roughly 79-84 vulnerabilities across Windows, Office, SQL Server, Azure, .NET, Edge, and other products. Microsoft said none of the addressed flaws were known to be actively exploited at release time, though two had been publicly disclosed.
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