Patch tracker / CVE reference / CVE-2026-21511
CVE-2026-21511
CVE-2026-21511 is a high severity Microsoft vulnerability with a CVSS score of 7.5. Microsoft has shipped the fix: deploy one of the 6 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.
High severity Microsoft vulnerability, CVSS 7.5. Fixed by 6 Microsoft security updates.
Risk summary
Senserva AI Opinion for CVE-2026-21511
CVE-2026-21511 is a spoofing flaw carrying an Outlook title but listed as affecting SharePoint Enterprise Server 2016, SharePoint Server 2019, and Office 2019 32-bit editions, so confirm which of these you actually run before assuming Outlook alone is at issue. It rates High severity at CVSS 7.5, but EPSS puts exploit probability at only 4 percent, it is not in CISA KEV, and there is no known ransomware use. Spoofing bugs typically let an attacker misrepresent content or identity, which matters most where these servers face users who trust internal mail and document sources.
Do this: Inventory your SharePoint 2016, SharePoint 2019, and Office 2019 32-bit installs and apply Microsoft's patch for CVE-2026-21511 during your next maintenance window.
AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-21511
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Updated August 7, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Full tracking and change history for CVE-2026-21511
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
Exploitation and severity
Not in the CISA KEV catalog. EPSS exploit probability 3.6%. CVSS 7.5 (High).
This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.
Official patch(es) for CVE-2026-21511
Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5002833, KB5002834, KB5002836, KB5002839, KB5002840, KB5002841 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.
Apply the Microsoft security updates below to fix CVE-2026-21511. Each KB page carries the Microsoft Update Catalog download, Microsoft's known issues for the update, a copy-paste PowerShell check for whether it is installed, and the Senserva AI read.
Affected products
Fixed by the same updates
If you are patching CVE-2026-21511, the same updates also fix these:
Authoritative references
Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.