CVE-2026-103577 Microsoft QUIC Security Feature Bypass Vulnerability
An attacker can bypass security features in Microsoft QUIC due to insecure default variable initialization, affecting Windows and Server environments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-103577?
CVE-2026-103577 is a high-severity vulnerability in Microsoft Windows 11 23h2, published on 13 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Insecure default variable initialization in Microsoft QUIC allows an unauthorized attacker to bypass a security feature over a network.
Weakness: CWE-453
Which versions are affected by CVE-2026-103577?
It affects 7 products.
Products include Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows 11 26h1, Microsoft Windows 11 26h2, Microsoft Windows Server 2022 and 1 more.
How do I fix CVE-2026-103577?
No fix has been published for CVE-2026-103577 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-103577 being exploited?
There is no known exploitation of CVE-2026-103577 in the wild and no public exploit code.
Other vulnerabilities in Microsoft Windows 11 23h2
- CVE-2026-81963 Microsoft Windows Link Following
- CVE-2026-100219 Microsoft QUIC Remote Code Execution Vulnerability
- CVE-2026-96909 Windows BitLocker Remote Code Execution Vulnerability
- CVE-2026-62815 Microsoft QUIC Remote Code Execution Vulnerability
- CVE-2026-45657 Windows Kernel Remote Code Execution Vulnerability
Sources
Also known as GHSA-74jh-9hhr-rxh5.