Patch tracker / CVE reference / CVE-2026-40372

CVE-2026-40372

CVE-2026-40372 is a critical severity Microsoft vulnerability with a CVSS score of 9.1. Its EPSS score puts the probability of exploitation in the next 30 days at 11%. Microsoft has shipped the fix: deploy the update 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 9.1. Fixed by 1 Microsoft security update.

Senserva AI read on CVE-2026-40372Official patches for CVE-2026-40372Change historyAdmin questions

Risk summary

CVSS base
9.1
EPSS exploit probability
11%
Severity
Critical

Senserva AI Opinion for CVE-2026-40372

An Elevation of Privilege flaw in ASP.NET Core 10.0, rated Critical Severity at CVSS 9.1 with an 11% EPSS. Because this affects the newest ASP.NET Core release line, the exposed population is early adopters: teams that moved quickly to 10.0 now need to move quickly again. As with all framework flaws, remediation means updating packages and redeploying every application on the vulnerable runtime, not installing one patch.

Do this: Identify services built on ASP.NET Core 10.0, update the runtime, and redeploy, prioritizing anything internet-facing.

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

Senserva AI Opinion and rich prompt for CVE-2026-40372

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

Patch this cycle
Not confirmed exploited yet, but the 30-day exploit probability is high (EPSS 11%).
Fixed by KB5091596. 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 August 7, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2026-40372

Published
2026-04-21
Last revised
2026-04-28
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 11%. CVSS 9.1 (Critical).

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

Official patch(es) for CVE-2026-40372

Elevated priority: high severity or a meaningful exploitation probability, sooner if an affected product is internet-facing. In Intune or Defender, confirm whether the fixing update KB5091596 are installed across the affected products. Senserva does this automatically across your tenant and flags every missing patch.

Apply the Microsoft security update below to fix CVE-2026-40372. 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.

KB5091596

Affected products

Authoritative references

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

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

New to a term on this page? CVE, KB, KEV, CVSS, and EPSS are each explained once, on the Senserva security lexicon. Reference: Microsoft CVE and vulnerability management and the Microsoft patching guide.
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.