Patch tracker / CVE reference / CVE-2026-20877
CVE-2026-20877
Updated July 22, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Critical severity Microsoft vulnerability, CVSS 9.8. Fixed by 7 Microsoft security updates.
All about CVE-2026-20877: the Senserva AI read, whether it is exploited, the official patches, its change history, and the questions admins ask.
CVE-2026-20877 is a critical severity Microsoft vulnerability with a CVSS score of 9.8. Its EPSS score puts the probability of exploitation in the next 30 days at 73%. Microsoft has shipped the fix: deploy one of the 7 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.
Risk summary
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Senserva AI Opinion for CVE-2026-20877
Another of the grouped Management Services flaws, with the same profile: elevation of privilege on Windows 10 1809 and Windows Server 2019, Critical Severity at CVSS 9.8, and 73 percent EPSS. The repetition is the message; this component's attack surface was systematically mined. Unpatched Server 2019 systems are carrying not one but a stack of equivalent escalation paths.
Do this: Treat any Server 2019 host missing this update as high risk and remediate or isolate it this week.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2026-20877
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2026-20877
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 73%. CVSS 9.8 (Critical).
This CVE is among the top 25% of tracked Microsoft CVEs by EPSS exploit probability.
Official patch(es) for CVE-2026-20877
High priority: EPSS puts the odds of near-term exploitation high. In Intune or Defender, confirm whether the fixing updates KB5073379, KB5073450, KB5073455, KB5073457, KB5073723, KB5073724, KB5074109 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-2026-20877. 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
Common questions about CVE-2026-20877
Is CVE-2026-20877 actively exploited?
It is not currently listed in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score puts the probability of exploitation in the next 30 days at 73%.
What patch fixes CVE-2026-20877?
Microsoft fixed CVE-2026-20877 in KB5073379, KB5073450, KB5073455, KB5073457, KB5073723, KB5073724, KB5074109. Download from the Microsoft Update Catalog, or let Intune, Windows Update, or WSUS deliver it.
Which products are affected by CVE-2026-20877?
Windows 10 Version 1809 for 32-bit Systems, Windows 11 Version 25H2 for ARM64-based Systems, Windows 11 Version 25H2 for x64-based Systems.
Can I ask my own AI about CVE-2026-20877?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2026-20877'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).
Fixed by the same updates
If you are patching CVE-2026-20877, 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.
