Patch tracker / CVE reference / CVE-2025-21387

CVE-2025-21387

CVE-2025-21387 is a high severity Microsoft vulnerability with a CVSS score of 7.8. Microsoft has shipped the fix: deploy one of the 3 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

High

High severity Microsoft vulnerability, CVSS 7.8. Fixed by 3 Microsoft security updates.

Senserva AI read on CVE-2025-21387 Official patches for CVE-2025-21387 Change history Admin questions

Risk summary

CVSS base

7.8

EPSS exploit probability

1.1%

Severity

High

Senserva AI Opinion for CVE-2025-21387

Excel remote code execution affecting Office Online Server and Office 2019, rated High Severity at CVSS 7.8, EPSS 1 percent. The consistent pattern across these fixes, hostile spreadsheet in, attacker code out, means user-facing controls like Protected View plus prompt patching are the whole defense.

Do this: Keep Protected View and file-block policies enforced while confirming the update reached every Office install.

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

Senserva AI Opinion and rich prompt for CVE-2025-21387

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-2025-21387 (source: https://senserva.com/cve/CVE-2025-21387.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2025-21387: High severity Microsoft vulnerability, CVSS 7.8
- EPSS 30-day exploitation probability: 1.1%
- Actively exploited (CISA KEV): no
- Fixed by: KB5002679, KB5002684, KB5002687
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 1%.

Fixed by KB5002679 and 2 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.

Updated August 7, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2025-21387

Published

2025-02-11

Last revised

2025-02-11

Changes tracked

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 1.1%. CVSS 7.8 (High).

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

Official patch(es) for CVE-2025-21387

Moderate priority: schedule it in your normal patch cycle. In Intune or Defender, confirm whether the fixing updates KB5002679, KB5002684, KB5002687 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-2025-21387. 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.

KB5002679 KB5002684 KB5002687

Affected products

Fixed by the same updates

If you are patching CVE-2025-21387, the same updates also fix these:

CVE-2025-21381 CVE-2025-21386 CVE-2025-21390 CVE-2025-21394

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.