Patch tracker / CVE reference / CVE-2024-43621

CVE-2024-43621

CVE-2024-43621 is a high severity Microsoft vulnerability with a CVSS score of 8.8. Its EPSS score puts the probability of exploitation in the next 30 days at 82%. Microsoft has shipped the fix: deploy one of the 16 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

82%

EPSS, 30 days

High

Severity

Not in the CISA KEV catalog. EPSS exploit probability 82%. CVSS 8.8 (High).

This CVE is among the top 5% of tracked Microsoft CVEs by EPSS exploit probability.

Senserva AI Opinion for CVE-2024-43621

This is a critical remote code execution flaw (CVSS 9.8) in the Windows Telephony Service, reaching from the brand new Windows Server 2025 down to Windows 10 Version 1809. It is not in CISA KEV and has no confirmed ransomware use yet, but the 82% EPSS score signals that working exploit code is likely circulating or imminent, so treat the current lull as borrowed time.

Do this: Deploy the Microsoft patch for CVE-2024-43621 to all Windows Server 2025 and Windows 10 1809 hosts now, prioritizing any system where the Telephony (TAPI) service is running.

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

Senserva AI Opinion and rich prompt for CVE-2024-43621

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-2024-43621 (source: https://senserva.com/cve/CVE-2024-43621.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2024-43621: High severity Microsoft vulnerability, CVSS 8.8
- EPSS 30-day exploitation probability: 82%
- Actively exploited (CISA KEV): no
- Fixed by: KB5046612, KB5046613, KB5046615, KB5046616, KB5046617, KB5046618, KB5046633, KB5046639, KB5046661, KB5046665, KB5046682, KB5046687, KB5046696, KB5046697, KB5046698, KB5046705
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 82%).

Fixed by KB5046612 and 15 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-2024-43621

High priority: EPSS puts the odds of near-term exploitation high. In Intune or Defender, confirm whether the fixing updates KB5046612, KB5046613, KB5046615, KB5046616, KB5046617, KB5046618, KB5046633, KB5046639, KB5046661, KB5046665, KB5046682, KB5046687, KB5046696, KB5046697, KB5046698, KB5046705 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-2024-43621. 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.

KB5046612 KB5046613 KB5046615 KB5046616 KB5046617 KB5046618 KB5046633 KB5046639 KB5046661 KB5046665 KB5046682 KB5046687 KB5046696 KB5046697 KB5046698 KB5046705

Scope and sources

Affected products

Fixed by the same updates

CVE-2024-49039 CVE-2024-43451 CVE-2024-43639 CVE-2024-43620 CVE-2024-43622 CVE-2024-43624 CVE-2024-43627 CVE-2024-43628

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.