CVE-2026-85790: Microsoft QUIC Information Disclosure Vulnerability

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-13 · updated 2026-10-31
Weakness: CWE-416

Description

Use after free in Microsoft QUIC allows an unauthorized attacker to disclose information over a network.

Affected products

Microsoft Native.Quic.Msquic.Schannel: before 2.6.2 — fixed in 2.6.2
Microsoft Visual Studio 2022 version 17.14: from 17.14.0 before 17.14.42 — fixed in 17.14.42
Microsoft Visual Studio 2026 version 18.9: from 18.10.0 before 18.10.4 — fixed in 18.10.4
Microsoft Windows 11: before 10.0.22631.7652 — fixed in 10.0.22631.7652
Microsoft Windows 11: before 10.0.26100.9711 — fixed in 10.0.26100.9711
Microsoft Windows 11 25H2: before 10.0.26200.9711 — fixed in 10.0.26200.9711
Microsoft Windows 11 version 26H1: before 10.0.28000.3231 — fixed in 10.0.28000.3231
Microsoft Windows 11 26H2: before 10.0.26300.9711 — fixed in 10.0.26300.9711
Microsoft Windows Server 2022: before 10.0.20348.5761 — fixed in 10.0.20348.5761
Microsoft Windows Server 2025: before 10.0.26100.33650 — fixed in 10.0.26100.33650
Microsoft.Native.Quic.MsQuic.Schannel: from 1.9.0 before 2.6.2 — fixed in 2.6.2
Microsoft Visual Studio 2026 version 18.10: from 18.10.0 before 18.10.4 — fixed in 18.10.4
Microsoft Visual Studio 2022 version 17.14: from 17.14.0 before 17.14.42 — fixed in 17.14.42
Microsoft Windows 11: from 10.0.22631.0 before 10.0.22631.7652 — fixed in 10.0.22631.7652
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.9711 — fixed in 10.0.26100.9711
Microsoft Windows 11 25H2: from 10.0.26200.0 before 10.0.26200.9711 — fixed in 10.0.26200.9711
Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.3231 — fixed in 10.0.28000.3231
Microsoft Windows 11 26H2: from 10.0.26300.0 before 10.0.26300.9711 — fixed in 10.0.26300.9711
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.5761 — fixed in 10.0.20348.5761
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.33650 — fixed in 10.0.26100.33650

How to fix

Upgrade to a fixed version: Microsoft Native.Quic.Msquic.Schannel 2.6.2; Microsoft Visual Studio 2022 version 17.14 17.14.42; Microsoft Visual Studio 2026 version 18.9 18.10.4; Microsoft Windows 11 10.0.22631.7652; Microsoft Windows 11 10.0.26100.9711; Microsoft Windows 11 25H2 10.0.26200.9711; Microsoft Windows 11 version 26H1 10.0.28000.3231; Microsoft Windows 11 26H2 10.0.26300.9711; Microsoft Windows Server 2022 10.0.20348.5761; Microsoft Windows Server 2025 10.0.26100.33650; Microsoft.Native.Quic.MsQuic.Schannel 2.6.2; Microsoft Visual Studio 2026 version 18.10 18.10.4. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85790

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