Summary
Impact: Security Feature Bypass. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
According to the CVSS metric, the attack vector is network (AV:N), privilege required is none (PR:N), and user interaction is none (UI:N). What is the target used in the context of the security feature bypass?
An attacker without existing privileges can remotely bypass authentication and obtain a successful login without additional user interaction.
According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
Successful exploitation of this vulnerability requires an attacker to have a deep understanding of the system. Successful exploitation is not guaranteed and depends on a combination of factors that might include the environment, system configuration, and the presence of additional security measures.
Security updates
10.0.26300.9711 — https://support.microsoft.com/help/5127648
10.0.20348.5761 — https://support.microsoft.com/help/5126655
10.0.22631.7652 — https://support.microsoft.com/help/5126653
10.0.26100.33650 — https://support.microsoft.com/help/5126646
10.0.28000.3231 — https://support.microsoft.com/help/5127646
Vulnerabilities 1
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High 7.5
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.
Revision history
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#1
Information published.
References
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CVE-2026-103577 Microsoft QUIC Security Feature Bypass Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-103577
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss