Patch tracker / CVE reference / CVE-2025-21183

CVE-2025-21183

CVE-2025-21183 is a high severity Microsoft vulnerability with a CVSS score of 7.4. Its EPSS score puts the probability of exploitation in the next 30 days at 24%. Microsoft has shipped the fix: deploy one of the 2 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

High

7.4

CVSS

24%

EPSS, 30 days

High

Severity

Not in the CISA KEV catalog. EPSS exploit probability 24%. CVSS 7.4 (High).

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

Senserva AI Opinion for CVE-2025-21183

CVE-2025-21183 is a companion ReFS Deduplication Service elevation-of-privilege flaw, High 8.8 with a 22 percent EPSS score on Server 2025 Core and Windows 11 24H2, paralleling CVE-2025-21182. Two dedup escalation paths in the same cycle mean storage hosts should be patched as a unit. It is not in CISA KEV and shows no ransomware use.

Do this: Patch both ReFS deduplication privilege bugs together on Windows 11 24H2 and Server 2025 Core storage hosts.

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

Senserva AI Opinion and rich prompt for CVE-2025-21183

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-2025-21183 (source: https://senserva.com/cve/CVE-2025-21183.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2025-21183: High severity Microsoft vulnerability, CVSS 7.4
- EPSS 30-day exploitation probability: 24%
- Actively exploited (CISA KEV): no
- Fixed by: KB5051987, KB5052105
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.

Patch this cycle

Not confirmed exploited yet, but the 30-day exploit probability is high (EPSS 24%).

Fixed by KB5051987 and 1 more (by build, listed below). Download from the Microsoft Update Catalog, or deploy via Windows Update, Intune, or WSUS.

Do this now: Patch in this maintenance window; do not let it slip to the next one.

Official patch(es) for CVE-2025-21183

Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. In Intune or Defender, confirm whether the fixing updates KB5051987, KB5052105 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-2025-21183. 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.

KB5051987 KB5052105

Scope and sources

Affected products

Fixed by the same updates

CVE-2025-21418 CVE-2025-21391 CVE-2025-21190 CVE-2025-21200 CVE-2025-21201 CVE-2025-21208 CVE-2025-21337 CVE-2025-21368

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.