Patch tracker / CVE reference / CVE-2026-27921

CVE-2026-27921

CVE-2026-27921 is a high severity Microsoft vulnerability with a CVSS score of 7.0. Its EPSS score puts the probability of exploitation in the next 30 days at 73%. Microsoft has shipped the fix: deploy one of the 11 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

High

7.0

CVSS v3

73%

EPSS, 30 days

High

Severity

Not in the CISA KEV catalog. EPSS exploit probability 73%. CVSS 7.0 (High).

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

Senserva AI Opinion for CVE-2026-27921

A second TDI Translation Driver (tdx.sys) escalation spans Windows 11 26H1 and Windows 10 1809 at 9.8 with 64 percent EPSS, mirroring its companion. The pairing means both the newest and legacy client builds need the tdx.sys fixes applied together to close the kernel-networking surface. Neither should be left half-patched.

Do this: Deploy CVE-2026-27921 with the other tdx.sys fix on Windows 11 26H1 and Windows 10 1809.

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

Senserva AI Opinion and rich prompt for CVE-2026-27921

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-2026-27921 (source: https://senserva.com/cve/CVE-2026-27921.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed once a day (early morning US Central)):
- CVE-2026-27921: High severity Microsoft vulnerability, CVSS 7.0
- EPSS 30-day exploitation probability: 73%
- Actively exploited (CISA KEV): no
- Fixed by: KB5082052, KB5082060, KB5082063, KB5082123, KB5082126, KB5082127, KB5082142, KB5082198, KB5082200, KB5083768, KB5083769
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 73%).

Fixed by KB5082052 and 10 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-2026-27921

High priority: EPSS puts the odds of near-term exploitation high. In Intune or Defender, confirm whether the fixing updates KB5082052, KB5082060, KB5082063, KB5082123, KB5082126, KB5082127, KB5082142, KB5082198, KB5082200, KB5083768, KB5083769 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-2026-27921. 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.

KB5082052 KB5082060 KB5082063 KB5082123 KB5082126 KB5082127 KB5082142 KB5082198 KB5082200 KB5083768 KB5083769

Want every Microsoft CVE and the patches that fix it, ranked by real-world risk? See the Microsoft Patch Tracker.

CVE-2026-27921

Risk summary

Official patch(es) for CVE-2026-27921

Scope and sources