Patch tracker / CVE reference / CVE-2026-21509
CVE-2026-21509
High severity Microsoft vulnerability, CVSS 7.8. Fixed by 1 Microsoft security update.
On this page, all about CVE-2026-21509: the Senserva AI read, whether it is exploited, the official patches, its change history, and the questions admins ask. Find every machine missing this see which of your devices still have this one, plus your complete patch state and all 650+ security checks with full reports, free: start your One Free Unlimited Audit. All you do is register.
CVE-2026-21509 is a high severity Microsoft vulnerability with a CVSS score of 7.8. It is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it in the wild, which makes it a fix-first item. Microsoft has shipped the fix: deploy the update below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.
Risk summary
Senserva AI Opinion for CVE-2026-21509
A 72% EPSS score distinguishes this Office security feature bypass, and CISA confirmed exploitation with a KEV entry on 2026-01-26. Office 2019 and Microsoft 365 Apps are affected, meaning virtually every desktop that opens documents. Bypass plus phishing attachment is the standard combination in the wild.
Do this: Push current Office updates to completion and re-enable any Protected View or macro policies users have weakened.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-21509
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2026-21509
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
Listed in the CISA Known Exploited Vulnerabilities catalog, confirmed exploited in the wild. EPSS exploit probability 72%. CVSS 7.8 (High).
This CVE is among the top 25% of tracked Microsoft CVEs by EPSS exploit probability, and one of 3 actively-exploited CVEs in January 2026.
Official patch(es) for CVE-2026-21509
Treat as urgent: it is being exploited in the wild (CISA KEV), so patch ahead of items that are not. In Intune or Defender, confirm whether the fixing update KB5002713 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.
Apply the Microsoft security update below to fix CVE-2026-21509. Each KB page links to the Microsoft Update Catalog download for every affected product.
Affected products
Common questions about CVE-2026-21509
Is CVE-2026-21509 actively exploited?
Yes. CVE-2026-21509 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed. Its EPSS exploit probability is 72%.
What patch fixes CVE-2026-21509?
Microsoft fixed CVE-2026-21509 in KB5002713. Download from the Microsoft Update Catalog, or let Intune, Windows Update, or WSUS deliver it.
Which products are affected by CVE-2026-21509?
Microsoft 365 Apps for Enterprise for 32-bit Systems, Microsoft Office 2019 for 32-bit editions, Microsoft Office 2019 for 64-bit editions.
Can I ask my own AI about CVE-2026-21509?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2026-21509's key facts: severity, CVSS, EPSS exploit probability, CISA KEV status, and the fixing KB. Copy it into Claude, ChatGPT, or Copilot for a triage plan; the data is refreshed three times a day (5 AM, 12:30 PM, and 7 PM US Central).
Authoritative references
Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.
