OnlyPatch
Microsoft QUIC

CVE-2026-62815 — Microsoft QUIC Remote Code Execution Vulnerability

Critical CVSS 9.8 EPSS 0.00936 2026-08 archive

Executive Summary

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

Overview

9.8
CVSS CRITICAL
Critical
MS Severity
Not Exploited
MS Exploit Status
N/A
MS Exploit Likelihood
Category Remote Code Execution
Released Aug 11 2026
Last Updated Aug 11 2026
Publicly Disclosed No
CISA KEV Not Listed
Known Exploits None Known
EPSS Score 0.00936 — 0.57742 percentile
NVD CVSS 9.8 CRITICAL — matches MSRC

CVSS Vector

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
ATTACK VECTOR
Network
ATTACK COMPLEXITY
Low
PRIVILEGES REQUIRED
None
USER INTERACTION
None
SCOPE
Unchanged
CONFIDENTIALITY
High
INTEGRITY
High
AVAILABILITY
High
EXPLOIT CODE MATURITY
Unproven
REMEDIATION LEVEL
Official Fix
REPORT CONFIDENCE
Confirmed
Temporal Score: 8.5

EPSS Score

0.00936
probability of exploitation in the next 30 days
0.57742 percentile - updated 2026-08-14
View on FIRST.org

Affected Products

4 affected products
Product KB Article Severity Impact Restart Required
Windows 11 Version 23H2 for ARM64-based Systems 5120240 (Security Update) Critical Remote Code Execution Yes
Windows 11 Version 23H2 for x64-based Systems 5120240 (Security Update) Critical Remote Code Execution Yes
Windows 11 Version 24H2 for ARM64-based Systems 5120994 (Security Hotpatch Update) 5121003 (Security Update) Critical Remote Code Execution 5101650 Base: 9.8 Temporal: 8.5 Vector: 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 10.0.26100.9106 10.0.26100.9168 Yes None Windows 11 Version 24H2 for x64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Critical Remote Code Execution 5101650 Base: 9.8 Temporal: 8.5 Vector: 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 10.0.26100.9168 10.0.26000.9106 Yes None Windows 11 Version 25H2 for ARM64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Critical Remote Code Execution 5101650 Base: 9.8 Temporal: 8.5 Vector: 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 10.0.26200.9168 10.0.26100.9106 Yes None Windows 11 Version 25H2 for x64-based Systems 5121003 (Security Update) 5120994 (Security Hotpatch Update) Critical Remote Code Execution 5101650 Base: 9.8 Temporal: 8.5 Vector: 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 10.0.26200.9168 10.0.26100.9106 Yes None Windows 11 Version 26H1 for ARM64-based Systems 5121000 (Security Update) Critical Remote Code Execution Yes
Windows 11 version 26H1 for x64-based Systems 5121000 (Security Update) Critical Remote Code Execution Yes

Patches

2 patches
Article Type Restart
5120240 Security Update Yes
5121000 Security Update Yes

Known Exploits

On This Page