# CVE-2026-72940 — Microsoft Windows 11 version 23H2

> As of 2026-10-08, CVE-2026-72940 is a HIGH-severity vulnerability in Microsoft Windows 11 version 23H2, CVSS v3.1 8.8, EPSS 0.8% (55.9th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-72940, most recently “Microsoft September 2026 Patch Tuesday — 999 CVEs, 3 actively exploited zero-days (CVE-2026-85880, CVE-2026-81963, CVE-2026-85046)”.

**Last updated:** 2026-10-08

## What is CVE-2026-72940?

Heap-based buffer overflow in Windows Schannel allows an unauthorized attacker to execute code over a network.

The record classifies CVE-2026-72940 under weakness class [CWE-122](https://intel.threadlinqs.com/cwe/CWE-122). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs a user to take an action first, and has high impact on confidentiality, integrity, availability. 8 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 44 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 8.8 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **EPSS (FIRST):** 0.8% probability of exploitation in the next 30 days, higher than 55.9% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 6.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-08, last modified 2026-10-08

## Is CVE-2026-72940 being exploited?

It currently carries a trending score of 41 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Microsoft](https://intel.threadlinqs.com/vendors/microsoft): Windows 11 version 23H2, Windows 11 Version 23H2, Windows 11 Version 24H2, Windows 11 Version 25H2, Windows 11 version 26H1, Windows Server 2022, Windows Server 2025, Windows Server 2025 (Server Core installation)

## How to fix CVE-2026-72940

No vendor patch reference has been recorded for CVE-2026-72940 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-72940

1 tracked threat in the Threadlinqs corpus references CVE-2026-72940, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Microsoft September 2026 Patch Tuesday — 999 CVEs, 3 actively exploited zero-days (CVE-2026-85880, CVE-2026-81963, CVE-2026-85046)](https://intel.threadlinqs.com/threat/TL-2026-2407) — CRITICAL · 2026-09-08

## Sources

Enriched from CVE.org, FIRST EPSS. Last verified by Threadlinqs on 2026-10-10.

**Vendor advisory and patch**

- [msrc.microsoft.com — vendor advisory](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-72940)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-72940
Full detection coverage and IOCs for threats exploiting CVE-2026-72940 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp