CVE-2026-103577
Microsoft QUIC Security Feature Bypass Vulnerability
Insecure default variable initialization in Microsoft QUIC allows an unauthorized attacker to bypass a security feature over a network.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
Microsoft QUIC Security Feature Bypass Vulnerability
Insecure default variable initialization in Microsoft QUIC allows an unauthorized attacker to bypass a security feature over a network.
- Record
CVE-2026-103577- CVSS 3.1
- 7.5 High
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 - Weakness
- CWE-453
- Updated
- 2026-11-02
EUVDEUVD-2026-100390
Insecure default variable initialization in Microsoft QUIC allows an unauthorized attacker to bypass a security feature over a network.
- Record
EUVD-2026-100390- CVSS 3.1
- 7.5 High
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-74jh-9hhr-rxh5
Insecure default variable initialization in Microsoft QUIC allows an unauthorized attacker to...
Insecure default variable initialization in Microsoft QUIC allows an unauthorized attacker to bypass a security feature over a network.
- Record
GHSA-74jh-9hhr-rxh5- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:H - Weakness
- CWE-453
- Updated
- 2026-11-02
NVD
Insecure default variable initialization in Microsoft QUIC allows an unauthorized attacker to bypass a security feature over a network.
- Record
CVE-2026-103577- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:H - Weakness
- CWE-453
- Updated
- 2026-11-02
Affected products
- microsoft windows 11 version 23h2
- microsoft windows 11 version 24h2
- microsoft windows 11 version 25h2
- microsoft windows 11 version 26h1
- microsoft windows 11 version 26h2
- microsoft windows server 2022
- microsoft windows server 2025
- microsoft windows server 2025 (server core installation)
- microsoft windows 11 23h2
- microsoft windows 11 24h2
- microsoft windows 11 25h2
- microsoft windows 11 26h1
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History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-103577 is a high vulnerability (CVSS 7.5) in Microsoft Windows 11 Version 23h2, published October 13, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.57%, the 47th percentile. No source names a fixed version.