Patch tracker / CVE reference / CVE-2025-21393

CVE-2025-21393

CVE-2025-21393 is a medium severity Microsoft vulnerability with a CVSS score of 6.3. Microsoft has shipped the fix: deploy one of the 5 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

Medium

6.3

CVSS v3

1.8%

EPSS, 30 days

Medium

Severity

Not in the CISA KEV catalog. EPSS exploit probability 1.8%. CVSS 6.3 (Medium).

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

Senserva AI Opinion for CVE-2025-21393

SharePoint Server, across the same Enterprise 2016 through Subscription Edition range as the other SharePoint findings in this batch, has a spoofing vulnerability here rated High 7.8 with a low 2 percent EPSS score. Compared to the SharePoint denial of service bug elsewhere in this list, which carries a much higher 51 percent EPSS, this spoofing issue looks like a lower near-term priority within the SharePoint patch set. It is not confirmed exploited or tied to ransomware.

Do this: Patch SharePoint farms for this alongside the other SharePoint CVEs in this batch, but rank it behind the higher-EPSS SharePoint denial of service fix.

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

Senserva AI Opinion and rich prompt for CVE-2025-21393

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-2025-21393 (source: https://senserva.com/cve/CVE-2025-21393.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2025-21393: Medium severity Microsoft vulnerability, CVSS 6.3
- EPSS 30-day exploitation probability: 1.8%
- Actively exploited (CISA KEV): no
- Fixed by: KB5002666, KB5002667, KB5002671, KB5002672, KB5002676
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 2%.

Fixed by KB5002666 and 4 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-2025-21393

Lower priority: patch in your normal cycle. In Intune or Defender, confirm whether the fixing updates KB5002666, KB5002667, KB5002671, KB5002672, KB5002676 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-2025-21393. 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.

KB5002666 KB5002667 KB5002671 KB5002672 KB5002676

Scope and sources

Affected products

Fixed by the same updates

CVE-2025-21344 CVE-2025-21348

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.