Vulnerability · Published Oct 13, 2026 · Assigned by microsoft
CVE-2026-103577Microsoft QUIC Security Feature Bypass Vulnerability
High 7.5
In plain English
A high-severity security flaw in Windows 11 version 23H2 from Microsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 52.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Insecure default variable initialization in Microsoft QUIC allows an unauthorized attacker to bypass a security feature over a network.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 11 version 23H2 | 10.0.22631.0 – before 10.0.22631.7652 |
| Microsoft | Windows 11 Version 23H2 | 10.0.22631.0 – before 10.0.22631.7652 |
| Microsoft | Windows 11 Version 24H2 | 10.0.26100.0 – before 10.0.26100.9711 |
| Microsoft | Windows 11 Version 25H2 | 10.0.26200.0 – before 10.0.26200.9711 |
| Microsoft | Windows 11 version 26H1 | 10.0.28000.0 – before 10.0.28000.3231 |
| Microsoft | Windows 11 Version 26H2 | 10.0.26300.0 – before 10.0.26300.9711 |
| Microsoft | Windows Server 2022 | 10.0.20348.0 – before 10.0.20348.5761 |
| Microsoft | Windows Server 2025 | 10.0.26100.0 – before 10.0.26100.33650 |
| Microsoft | Windows Server 2025 (Server Core installation) | 10.0.26100.0 – before 10.0.26100.33650 |
Weakness: CWE-453 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:H/E:U/RL:O/RC:C
References
- Microsoft QUIC Security Feature Bypass Vulnerability vendor-advisory, patch