Microsoft’s latest Patch Tuesday updates fix 165 vulnerabilities, including a SharePoint zero-day that has been exploited in the wild.
The exploited SharePoint Server vulnerability is tracked as CVE-2026-32201 and it has been described as a spoofing issue.
Microsoft assigned it an ‘important’ severity rating with a CVSS score of 6.5.
“Improper input validation in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network,” Microsoft said, adding that an attacker may be able to exploit the flaw to access sensitive information and alter it.
It’s unclear who is behind the zero-day attacks exploiting CVE-2026-32201 and what their motivation is. At the time of writing no information appears to be available and Microsoft has yet to say who reported the security hole.
However, based on the vendor’s brief description it’s possible that CVE-2026-32201 is being chained with other weaknesses.
SharePoint vulnerabilities are often exploited in the wild. CISA’s Known Exploited Vulnerabilities (KEV) catalog currently includes 10 SharePoint flaws.
CVE-2026-32201 has already been added to CISA’s KEV list, and federal agencies have been instructed to patch it by April 28.
Of the remaining vulnerabilities patched by Microsoft with its April 2026 Patch Tuesday updates, 19 have an exploitability rating of ‘exploitation more likely’, which indicates that they may end up being exploited in attacks.
One of these vulnerabilities is CVE-2026-33825, a Microsoft Defender privilege-escalation issue that the tech giant says was publicly disclosed before patches were released. This is believed to be the vulnerability dubbed BlueHammer, which a disgruntled researcher recently made public.
Security holes in Windows components such as Boot Loader, Active Directory, Remote Desktop, Hello, Storage Space Controllers, Search, TDI Translation Driver, BitLocker, Management Console, TCP/IP, Common Log File System Driver, UPnP Device Host, COM, Shell, Function Discovery Service, and Desktop Window Manager are also more likely to be exploited in the future.
Satnam Narang, senior staff research engineer at Tenable, said this is the second-largest Patch Tuesday ever, just shy of the record set in October 2025.
Adobe has patched more than 50 vulnerabilities across 11 products with its latest Patch Tuesday fixes.
*updated to note that CVE-2026-33825 is believed to be the vulnerability dubbed BlueHammer.
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