Patch tracker / CVE reference / CVE-2025-21304

CVE-2025-21304

CVE-2025-21304 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 81%. 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.

Critical

Critical severity Microsoft vulnerability, CVSS 9.8. Fixed by 3 Microsoft security updates.

Senserva AI read on CVE-2025-21304Official patches for CVE-2025-21304Change historyAdmin questions

Risk summary

CVSS base
9.8
EPSS exploit probability
81%
Severity
Critical
Patch this cycle
Not confirmed exploited yet, but the 30-day exploit probability is high (EPSS 81%).
Fixed by KB5049981 and 2 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.

Updated July 24, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Senserva AI Opinion for CVE-2025-21304

Most DWM Core Library bugs land at High Severity; this one is Critical at CVSS 9.8 with an 81 percent EPSS score, on Windows 10 1809 and Windows Server 2019. That combination makes it the DWM fix to anchor the deployment around rather than one more entry in the list.

Do this: Fast-track the update on interactive systems, especially Remote Desktop session hosts where DWM serves many users at once.

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

Senserva AI Opinion and rich prompt for CVE-2025-21304

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

Full tracking and change history for CVE-2025-21304

Published
2025-01-14
Last revised
2025-01-14
Changes tracked
1

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 81%. CVSS 9.8 (Critical).

This CVE is among the top 25% of tracked Microsoft CVEs by EPSS exploit probability.

Official patch(es) for CVE-2025-21304

High priority: EPSS puts the odds of near-term exploitation high. In Intune or Defender, confirm whether the fixing updates KB5049981, KB5049993, KB5050008 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-2025-21304. 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.

KB5049981KB5049993KB5050008

Affected products

Common questions about CVE-2025-21304

Is CVE-2025-21304 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 81%.

What patch fixes CVE-2025-21304?

Microsoft fixed CVE-2025-21304 in KB5049981, KB5049993, KB5050008. Download from the Microsoft Update Catalog, or let Intune, Windows Update, or WSUS deliver it.

Which products are affected by CVE-2025-21304?

Windows 10 Version 1809 for 32-bit Systems, Windows 10 Version 1809 for x64-based Systems, Windows Server 2019.

Can I ask my own AI about CVE-2025-21304?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2025-21304'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-2025-21304, the same updates also fix these:

CVE-2025-21333CVE-2025-21334CVE-2025-21335CVE-2024-49120CVE-2024-7344CVE-2025-21176CVE-2025-21189CVE-2025-21193

Authoritative references

Official CVE record (cve.org)NVD detailMicrosoft MSRCFIRST.org EPSS

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Lexicon: the terms on this page
CVE
Common Vulnerabilities and Exposures. A unique ID for one publicly known vulnerability, such as CVE-2025-1234.
KB
Microsoft Knowledge Base article. The identifier for a specific Microsoft update.
KEV
CISA Known Exploited Vulnerabilities. CVEs confirmed exploited in the wild. Fix these first.
CVSS
Common Vulnerability Scoring System. A standardized Severity score from 0 to 10.
EPSS
Exploit Prediction Scoring System. The probability a CVE will be exploited in the next 30 days.
MSRC
Microsoft Security Response Center. Microsoft's Patch Tuesday advisories and KB-to-CVE mapping.
NVD
National Vulnerability Database (NIST). Authoritative CVE metadata and CVSS scores.
Ransomware
The vulnerability is linked to known ransomware activity.
Reference: Microsoft CVE and vulnerability management, the full CVE-to-patch lookup ranked by real-world risk, and the Microsoft patching guide, how Intune, Windows Autopatch, Defender, and Azure Update Manager fit together.
Data notice: this page, the feeds, and the API are provided as is, for informational purposes only, without warranty of any kind. Senserva, LLC does not guarantee the accuracy, completeness, or timeliness of third-party data (MSRC, NVD, CISA KEV, EPSS) and accepts no liability for actions taken based on it; verify against the authoritative vendor advisory before acting. Built daily with Senserva Trustworthy AI. All use of this data is subject to the Senserva EULA.