# CVE-2026-62815 — Microsoft Windows 11 version 23H2

> As of 2026-10-08, CVE-2026-62815 is a CRITICAL-severity vulnerability in Microsoft Windows 11 version 23H2, CVSS v3.1 9.8, EPSS 0.9% (60.9th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-62815, most recently “Microsoft August 2026 Patch Tuesday: 400 Flaws Fixed, Including Lazarus-Exploited Zero-Day CVE-2026-68820 (AFD.sys) and Two Publicly Disclosed Zero-Days (CVE-2026-62832 "LegacyHive", CVE-2026-72971)”.

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

## What is CVE-2026-62815?

Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.

The record classifies CVE-2026-62815 under weakness class [CWE-416](https://intel.threadlinqs.com/cwe/CWE-416). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 8 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 60 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 9.8 — CRITICAL (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C`)
- **EPSS (FIRST):** 0.9% probability of exploitation in the next 30 days, higher than 60.9% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 7.3/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-08-11, last modified 2026-10-08

## Is CVE-2026-62815 being exploited?

It currently carries a trending score of 35 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-2026-62815

No vendor patch reference has been recorded for CVE-2026-62815 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-2026-62815

1 tracked threat in the Threadlinqs corpus references CVE-2026-62815, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Microsoft August 2026 Patch Tuesday: 400 Flaws Fixed, Including Lazarus-Exploited Zero-Day CVE-2026-68820 (AFD.sys) and Two Publicly Disclosed Zero-Days (CVE-2026-62832 "LegacyHive", CVE-2026-72971)](https://intel.threadlinqs.com/threat/TL-2026-1987) — CRITICAL · 2026-08-11

## 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-2026-62815)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-62815
Full detection coverage and IOCs for threats exploiting CVE-2026-62815 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp