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CVE-2026-62815

CRITICAL 9.8 ALL-YEARS

Published 2026-08-11 · Last modified 2026-10-21 · microsoft · NVD: Analyzed

Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.

ELEVATED IMPACT

Severe if exploited (CVSS 9.8), but no confirmed exploitation. Patch on a normal cadence.

Exploitation likelihood

1.0%chance of exploitation in 30 days · 62nd percentile

○ In CISA KEV○ Catalogued PoC◆ SSVC: exploitation none, automatable yes

Impact if exploited

9.8CVSS 3.1 · CRITICAL · CNA

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

Search for new PoCs

Search GitHub now — results may be empty or unverified.

Tracked sources are checked weekly for the full archive, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.

Affected

Vendors Microsoft

Products Windows 11 Version 23h2 Windows 11 Version 24h2 Windows 11 Version 25h2 Windows 11 Version 26h1 Windows Server 2022 Windows Server 2025 Windows Server 2025 (Server Core Installation) Windows 11 23h2 Windows 11 24h2 Windows 11 25h2 Windows 11 26h1

Weakness (CWE)

  • CWE-416: : Use After Free

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

References and research data (JSON)

Packages and version ranges

Each advisory describes its own package and affected ranges. A boundary applies to that range; it is not a universal upgrade recommendation.

  • Microsoft.Native.Quic.MsQuic.OpenSSL NuGet

    pkg:nuget/Microsoft.Native.Quic.MsQuic.OpenSSL

    ECOSYSTEM range
    • Introduced version (included): 2.5.3
    • Fixed boundary (excluded): 2.5.10
    Additional upstream package constraints
    {
  "database": {
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-92f5-vc22-8j33/GHSA-92f5-vc22-8j33.json"
  }
}
    GitHub Advisory Database · GHSA-92f5-vc22-8j33 · Updated 2026-09-08T20:55:58.931613Z
  • Microsoft.Native.Quic.MsQuic.Schannel NuGet

    pkg:nuget/Microsoft.Native.Quic.MsQuic.Schannel

    ECOSYSTEM range
    • Introduced version (included): 2.5.3
    • Fixed boundary (excluded): 2.5.10
    Additional upstream package constraints
    {
  "database": {
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-92f5-vc22-8j33/GHSA-92f5-vc22-8j33.json"
  }
}
    GitHub Advisory Database · GHSA-92f5-vc22-8j33 · Updated 2026-09-08T20:55:58.931613Z
  • Microsoft.Native.Quic.MsQuic.OpenSSL NuGet

    pkg:nuget/Microsoft.Native.Quic.MsQuic.OpenSSL

    ECOSYSTEM range
    • All earlier versions (introduced 0)
    • Fixed boundary (excluded): 2.4.19
    1 explicitly listed affected versions

    1.8.0

    Additional upstream package constraints
    {
  "database": {
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-92f5-vc22-8j33/GHSA-92f5-vc22-8j33.json"
  }
}
    GitHub Advisory Database · GHSA-92f5-vc22-8j33 · Updated 2026-09-08T20:55:58.931613Z
  • Microsoft.Native.Quic.MsQuic.Schannel NuGet

    pkg:nuget/Microsoft.Native.Quic.MsQuic.Schannel

    ECOSYSTEM range
    • All earlier versions (introduced 0)
    • Fixed boundary (excluded): 2.4.19
    1 explicitly listed affected versions

    1.8.0

    Additional upstream package constraints
    {
  "database": {
    "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-92f5-vc22-8j33/GHSA-92f5-vc22-8j33.json"
  }
}
    GitHub Advisory Database · GHSA-92f5-vc22-8j33 · Updated 2026-09-08T20:55:58.931613Z

Known Affected Software Configurations

VendorProductVersion range
MicrosoftWindows 11 23h2< 10.0.22631.7517
MicrosoftWindows 11 23h2< 10.0.22631.7517
MicrosoftWindows 11 24h2< 10.0.26100.9106
MicrosoftWindows 11 24h2< 10.0.26100.9106
MicrosoftWindows 11 25h2< 10.0.26200.9106
MicrosoftWindows 11 25h2< 10.0.26200.9106
MicrosoftWindows 11 26h1< 10.0.28000.2704
MicrosoftWindows 11 26h1< 10.0.28000.2704
MicrosoftWindows Server 2022< 10.0.20348.5440
MicrosoftWindows Server 2025< 10.0.26100.33222

All CVSS metrics

  • CRITICAL 9.8 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
  • CRITICAL 9.8 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Patches & mitigations

Advisories

Technical & other

Sources: NVD · CVE.org · All sources and attribution · EPSS