Patch tracker / CVE reference / CVE-2026-0390

CVE-2026-0390

CVE-2026-0390 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 56%. Microsoft has shipped the fix: deploy one of the 4 updates below from the Microsoft Update Catalog, and see where this CVE sits against the rest on the patch tracker.

Risk summary

Critical

9.8

CVSS

56%

EPSS, 30 days

Critical

Severity

Not in the CISA KEV catalog. EPSS exploit probability 56%. CVSS 9.8 (Critical).

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

Senserva AI Opinion for CVE-2026-0390

A second Secure Boot bypass this month, this UEFI-level flaw hits Windows 10 1809 and Server 2019 at CVSS 9.8 with 64 percent EPSS. Firmware-trust bypasses are prized by attackers because they enable bootkits that survive reinstalls and evade the operating system entirely. With two Secure Boot bypasses shipping at once, treat the firmware trust boundary on this branch as suspect until patched.

Do this: Roll out the UEFI Secure Boot fix to 1809 and Server 2019 machines, then confirm no unexpected changes to the Secure Boot allow/deny lists.

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

Senserva AI Opinion and rich prompt for CVE-2026-0390

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-2026-0390 (source: https://senserva.com/cve/CVE-2026-0390.html, data from MSRC, CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2026-0390: Critical severity Microsoft vulnerability, CVSS 9.8
- EPSS 30-day exploitation probability: 56%
- Actively exploited (CISA KEV): no
- Fixed by: KB5082123, KB5082142, KB5082198, KB5082200
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 56%).

Fixed by KB5082123 and 3 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-2026-0390

High priority: EPSS puts the odds of near-term exploitation high. In Intune or Defender, confirm whether the fixing updates KB5082123, KB5082142, KB5082198, KB5082200 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-2026-0390. 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.

KB5082123 KB5082142 KB5082198 KB5082200

Scope and sources

Affected products

Fixed by the same updates

CVE-2025-64720 CVE-2025-65018 CVE-2026-20806 CVE-2026-20928 CVE-2026-20930 CVE-2026-23670 CVE-2026-25250 CVE-2026-26151

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.