Patch tracker / CVE reference / CVE-2026-23673

CVE-2026-23673

CVE-2026-23673 is a high severity Microsoft vulnerability with a CVSS score of 8.8. Microsoft has shipped the fix: deploy one of the 14 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

High

8.8

CVSS

4.7%

EPSS, 30 days

High

Severity

Not in the CISA KEV catalog. EPSS exploit probability 4.7%. CVSS 8.8 (High).

This CVE is among the lower half of tracked Microsoft CVEs by EPSS exploit probability.

Senserva AI Opinion for CVE-2026-23673

This is a local elevation of privilege flaw in the ReFS filesystem driver on Windows 11 26H1 (ARM64 and x64) and Windows Server 2022, letting an authenticated user gain higher privileges through a ReFS-formatted volume. The CVSS 8.8 High rating reflects that an attacker only needs local access, and any host mounting ReFS storage is in scope. It is not in CISA KEV and EPSS puts exploitation at 4 percent, so this is a patch-on-cycle item rather than an emergency, but ReFS is common on Storage Spaces and backup targets.

Do this: Deploy the Microsoft patch to your 26H1 clients and Windows Server 2022 hosts, prioritizing systems that use ReFS volumes such as backup repositories and Storage Spaces servers.

AI-generated from public data, 2026-07-21. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2026-23673

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I am an IT admin assessing a vulnerability. Facts for CVE-2026-23673 (source: https://senserva.com/cve/CVE-2026-23673.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-23673: High severity Microsoft vulnerability, CVSS 8.8
- EPSS 30-day exploitation probability: 4.7%
- Actively exploited (CISA KEV): no
- Fixed by: KB5078734, KB5078736, KB5078737, KB5078740, KB5078752, KB5078766, KB5078774, KB5078775, KB5078883, KB5078885, KB5078938, KB5079420, KB5079466, KB5079473
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) What to patch or mitigate first. 4) How to check whether my devices are exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Schedule normally

No exploitation observed: not in the CISA KEV catalog, EPSS 5%.

Fixed by KB5078734 and 13 more (by build, listed below). Download from the Microsoft Update Catalog, or deploy via Windows Update, Intune, or WSUS.

Do this now: Deploy with your normal update cycle. This page refreshes daily; the verdict changes the day the data does.

Official patch(es) for CVE-2026-23673

Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5078734, KB5078736, KB5078737, KB5078740, KB5078752, KB5078766, KB5078774, KB5078775, KB5078883, KB5078885, KB5078938, KB5079420, KB5079466, KB5079473 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-2026-23673. 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.

KB5078734 KB5078736 KB5078737 KB5078740 KB5078752 KB5078766 KB5078774 KB5078775 KB5078883 KB5078885 KB5078938 KB5079420 KB5079466 KB5079473

Scope and sources

Affected products

Fixed by the same updates

CVE-2025-54518 CVE-2026-42825 CVE-2026-23667 CVE-2026-23668 CVE-2026-23669 CVE-2026-23671 CVE-2026-23672 CVE-2026-23674

Authoritative references

Official CVE record (cve.org)NVD detail Microsoft MSRC FIRST.org EPSS

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.