---
title: "CVE-2026-62815: Microsoft QUIC: Remote Code Execution Vulnerability"
url: https://erroneo.us/security/cve/CVE-2026-62815/
description: "CVE-2026-62815 (Microsoft.Native.Quic.MsQuic.OpenSSL (NuGet)): Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-08-11
date_modified: 2026-10-21
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-62815"
kev: false
cvss: 10.0
epss: 0.00974
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-62815: Microsoft QUIC: Remote Code Execution Vulnerability

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 1.0% , percentile 62: FIRST’s model estimates a 1.0% chance of exploitation activity in the next 30 days, higher than 62% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes Microsoft.Native.Quic.MsQuic.OpenSSL (NuGet) >= 2.5.3, < 2.5.10, fixed in 2.5.10 ; Microsoft.Native.Quic.MsQuic.Schannel (NuGet) >= 2.5.3, < 2.5.10, fixed in 2.5.10 ; Microsoft.Native.Quic.MsQuic.OpenSSL (NuGet) < 2.4.19, fixed in 2.4.19 ; Microsoft.Native.Quic.MsQuic.Schannel (NuGet) < 2.4.19, fixed in 2.4.19 . Check your lockfile, including transitive dependencies.

## What it is

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

## Affected packages

- NuGet `Microsoft.Native.Quic.MsQuic.OpenSSL` >= 2.5.3, < 2.5.10 → fixed: 2.5.10
- NuGet `Microsoft.Native.Quic.MsQuic.Schannel` >= 2.5.3, < 2.5.10 → fixed: 2.5.10
- NuGet `Microsoft.Native.Quic.MsQuic.OpenSSL` < 2.4.19 → fixed: 2.4.19
- NuGet `Microsoft.Native.Quic.MsQuic.Schannel` < 2.4.19 → fixed: 2.4.19

## Affected products (CVE record)

- Microsoft Windows 11 version 23H2: 10.0.22631.0 < 10.0.22631.7517
- Microsoft Windows 11 Version 23H2: 10.0.22631.0 < 10.0.22631.7517
- Microsoft Windows 11 Version 24H2: 10.0.26100.0 < 10.0.26100.9168
- Microsoft Windows 11 Version 25H2: 10.0.26200.0 < 10.0.26200.9168
- Microsoft Windows 11 version 26H1: 10.0.28000.0 < 10.0.28000.2704
- Microsoft Windows Server 2022: 10.0.20348.0 < 10.0.20348.5499
- Microsoft Windows Server 2025: 10.0.26100.0 < 10.0.26100.33296
- Microsoft Windows Server 2025 (Server Core installation): 10.0.26100.0 < 10.0.26100.33296

## Severity

- microsoft CVSS 3.1: 9.8 `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`
- GitHub CVSS 4.0: 10.0 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.97% probability of exploitation activity in the next 30 days; percentile 62.

## Sources

- [Microsoft QUIC Remote Code Execution Vulnerability](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62815)
- [GitHub Advisory GHSA-92f5-vc22-8j33](https://github.com/advisories/GHSA-92f5-vc22-8j33)
- [CVE.org record CVE-2026-62815](https://www.cve.org/CVERecord?id=CVE-2026-62815)
- [NVD entry CVE-2026-62815](https://nvd.nist.gov/vuln/detail/CVE-2026-62815)
- [github.com](https://github.com/microsoft/msquic/security/advisories/GHSA-92f5-vc22-8j33)
- [github.com](https://github.com/microsoft/msquic/pull/6217)
- [github.com](https://github.com/microsoft/msquic/pull/6219)
- [github.com](https://github.com/microsoft/msquic/pull/6220)
- [github.com](https://github.com/microsoft/msquic/commit/583e7d5b509bb0bfa3518482d98879b6eda41ad0)
- [github.com](https://github.com/microsoft/msquic/commit/9ff06b71fd4b4d5258361598ada5b24cbc1beb20)
- [github.com](https://github.com/microsoft/msquic/commit/e0f55b5fdc9fff0b4465976d066ebd22fb7e2b3b)
- [github.com](https://github.com/microsoft/msquic/releases/tag/v2.4.19)
- [github.com](https://github.com/microsoft/msquic/releases/tag/v2.5.10)

---
Source page: https://erroneo.us/security/cve/CVE-2026-62815/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt