EUVD-2026-56392
GHSA-2q33-cf8w-7q23
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Unauthenticated network-facing QUIC handler (AV:N/PR:N/UI:N) with full impact, but AC:H because reliable use-after-free RCE requires heap grooming and race timing versus a simple crash.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.
AnalysisAI
Remote code execution in Microsoft's QUIC transport implementation (MsQuic) allows an unauthenticated network attacker to run arbitrary code by triggering a use-after-free (CWE-416) in the QUIC protocol handler across supported Windows 11 (23H2/24H2/25H2/26H1) and Windows Server 2022/2025 builds. The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N) rates it 9.8 Critical, reflecting no authentication or user interaction and full compromise of confidentiality, integrity, and availability. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the target host be running and reachable on a Microsoft QUIC listener - i.e., an unpatched Windows 11 (23H2-26H1) or Windows Server 2022/2025 system with a QUIC-based service enabled and exposed, such as HTTP/3 in IIS/edge services or SMB over QUIC (typically UDP/443). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This is a genuine high-priority issue rather than an inflated high-CVSS score: the CVSS 3.1 vector is fully remote and unauthenticated with low attack complexity (AV:N/AC:L/PR:N/UI:N) and complete C/I/A impact, and the flaw sits in a network-facing OS transport component on widely deployed Windows platforms. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the Microsoft security update that raises each affected build to at least the fixed version listed in the EUVD data (Vendor-released patch confirmed available): Windows 11 23H2 to 10.0.22631.7517, 24H2 to 10.0.26100.9168, 25H2 to 10.0.26200.9168, 26H1 to 10.0.28000.2704, Windows Server 2022 to 10.0.20348.5499, and Windows Server 2025 (incl. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, conduct an immediate asset inventory to identify all Windows 11 (23H2/24H2/25H2/26H1) and Windows Server 2022/2025 systems potentially affected by CVE-2026-62815, prioritizing those with internet-facing or untrusted network exposure. …
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Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
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External POC / Exploit Code
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