CVE-2026-62815: Microsoft QUIC Remote Code Execution Vulnerability

CRITICAL
Advisory Identifier: GHSA-92f5-vc22-8j33
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CVSS 9.8
CWE-416
Published
Advisory Summary

CVE-2026-62815 is a CRITICAL (CVSS 9.8) remote code execution vulnerability (CWE-416: Use After Free) affecting Microsoft QUIC libraries in the NuGet ecosystem. The issue involves remote code execution vulnerability. Remediation is available by upgrading affected packages to version 2.4.19, 2.5.10.

CVE-2026-62815 at a Glance

CVE Identifier CVE-2026-62815
GHSA Identifier GHSA-92f5-vc22-8j33
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-416: Use After Free
Affected Product Microsoft QUIC
Package Ecosystem NuGet
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-62815

To remediate this vulnerability, upgrade all affected Microsoft QUIC dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Microsoft.Native.Quic.MsQuic.OpenSSL fixed: 2.4.19 
Upgrade Microsoft.Native.Quic.MsQuic.OpenSSL to 2.4.19
Microsoft.Native.Quic.MsQuic.Schannel fixed: 2.4.19 
Upgrade Microsoft.Native.Quic.MsQuic.Schannel to 2.4.19
Microsoft.Native.Quic.MsQuic.OpenSSL fixed: 2.5.10 
Upgrade Microsoft.Native.Quic.MsQuic.OpenSSL to 2.5.10
Microsoft.Native.Quic.MsQuic.Schannel fixed: 2.5.10 
Upgrade Microsoft.Native.Quic.MsQuic.Schannel to 2.5.10
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for Microsoft.Native.Quic.MsQuic.OpenSSL

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-62815, inspect your project dependencies for Microsoft QUIC:

inspect dependencies for Microsoft.Native.Quic.MsQuic.OpenSSL

Analyze the terminal output to locate any version of Microsoft QUIC in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.4.19), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-416: Use After Free, where the product reuses or references memory after it has been freed. at some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. In Microsoft QUIC, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

# Summary Use after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network. # Details New network path creations and removals triggered by incoming packets can lead to a pointer invalidation. ## Patches - Guard path promotion [e0f55b5](https://github.com/microsoft/msquic/commit/e0f55b5fdc9fff0b4465976d066ebd22fb7e2b3b) # Impact An unauthenticated attacker could exploit this vulnerability by sending a specially crafted packet to an affected service over the network. Successful exploitation could allow the attacker to execute code on the target system. No authentication or user interaction is required.

CVE-2026-62815 Affected Microsoft QUIC Versions

4 component(s)
Fixed Versions:
2.4.192.5.10
Product / Package Ecosystem Affected Versions Fixed Version
Microsoft.Native.Quic.MsQuic.OpenSSL
nuget/Microsoft.Native.Quic.MsQuic.OpenSSL
NuGet
< 2.4.19
2.4.19
Microsoft.Native.Quic.MsQuic.Schannel
nuget/Microsoft.Native.Quic.MsQuic.Schannel
NuGet
< 2.4.19
2.4.19
Microsoft.Native.Quic.MsQuic.OpenSSL
nuget/Microsoft.Native.Quic.MsQuic.OpenSSL
NuGet
≥ 2.5.3
< 2.5.10
2.5.10
Microsoft.Native.Quic.MsQuic.Schannel
nuget/Microsoft.Native.Quic.MsQuic.Schannel
NuGet
≥ 2.5.3
< 2.5.10
2.5.10

References

GitHub Advisory / Wiki ADVISORY
https://github.com/microsoft/msquic/security/advisories/GHSA-92f5-vc22-8j33
NVD — CVE-2026-62815 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-62815
Microsoft QUIC Source Repository REPOSITORY
https://github.com/microsoft/msquic/pull/6217
Microsoft QUIC Source Repository REPOSITORY
https://github.com/microsoft/msquic/pull/6219
Microsoft QUIC Source Repository REPOSITORY
https://github.com/microsoft/msquic/pull/6220
Security Fix Commit FIX COMMIT
https://github.com/microsoft/msquic/commit/583e7d5b509bb0bfa3518482d98879b6eda41ad0
Security Fix Commit FIX COMMIT
https://github.com/microsoft/msquic/commit/9ff06b71fd4b4d5258361598ada5b24cbc1beb20
Security Fix Commit FIX COMMIT
https://github.com/microsoft/msquic/commit/e0f55b5fdc9fff0b4465976d066ebd22fb7e2b3b
Microsoft QUIC Source Repository REPOSITORY
https://github.com/microsoft/msquic
Microsoft QUIC Release RELEASE
https://github.com/microsoft/msquic/releases/tag/v2.4.19
Microsoft QUIC Release RELEASE
https://github.com/microsoft/msquic/releases/tag/v2.5.10
msrc.microsoft.com/update-guide/vulner... WEB
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62815

Frequently Asked Questions

What is CVE-2026-62815?
CVE-2026-62815 is a security vulnerability in Microsoft QUIC involving Remote Code Execution Vulnerability under CWE-416: Use After Free.
Which Microsoft QUIC versions are affected?
Affected versions include releases prior to 2.4.19, 2.5.10 across affected packages: Microsoft.Native.Quic.MsQuic.OpenSSL, Microsoft.Native.Quic.MsQuic.Schannel.
What version fixes CVE-2026-62815?
Upgrading to 2.4.19, 2.5.10 (or the latest patched release for your respective branch) resolves the vulnerability.
Is Microsoft.Native.Quic.MsQuic.OpenSSL affected?
Yes, Microsoft.Native.Quic.MsQuic.OpenSSL is affected in releases prior to 2.4.19, 2.5.10. Upgrade your dependency to 2.4.19, 2.5.10 or later.
Is Microsoft.Native.Quic.MsQuic.Schannel affected?
Yes, Microsoft.Native.Quic.MsQuic.Schannel is affected in releases prior to 2.4.19, 2.5.10. Upgrade your dependency to 2.4.19, 2.5.10 or later.
What is the CVSS score of CVE-2026-62815?
CVE-2026-62815 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-62815?
CVE-2026-62815 is classified under CWE-416: Use After Free (The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.).
How can I check NuGet dependencies for CVE-2026-62815?
Run the dependency tree command: 'inspect dependencies for Microsoft.Native.Quic.MsQuic.OpenSSL'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-92f5-vc22-8j33",
  "modified" : "2026-09-08T20:27:02Z",
  "published" : "2026-09-08T20:27:02Z",
  "aliases" : [ "CVE-2026-62815" ],
  "summary" : "Microsoft QUIC: Remote Code Execution Vulnerability",
  "details" : "# Summary\nUse after free in Microsoft QUIC allows an unauthorized attacker to execute code over a network.\n\n# Details\n\nNew network path creations and removals triggered by incoming packets can lead to a pointer invalidation.\n\n## Patches\n\n- Guard path promotion [e0f55b5](https://github.com/microsoft/msquic/commit/e0f55b5fdc9fff0b4465976d066ebd22fb7e2b3b)\n\n# Impact\n\nAn unauthenticated attacker could exploit this vulnerability by sending a specially crafted packet to an affected service over the network. Successful exploitation could allow the attacker to execute code on the target system. No authentication or user interaction is required.",
  "severity" : [ {
    "type" : "CVSS_V3",
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  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H"
  } ],
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    },
    "ranges" : [ {
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      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "NuGet",
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    },
    "ranges" : [ {
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      "events" : [ {
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    } ]
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      }, {
        "fixed" : "2.4.19"
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    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
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  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-62815"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/microsoft/msquic/pull/6217"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/microsoft/msquic/pull/6219"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/microsoft/msquic/pull/6220"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/microsoft/msquic/commit/583e7d5b509bb0bfa3518482d98879b6eda41ad0"
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    "url" : "https://github.com/microsoft/msquic/commit/9ff06b71fd4b4d5258361598ada5b24cbc1beb20"
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  }, {
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    "url" : "https://github.com/microsoft/msquic/releases/tag/v2.4.19"
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    "url" : "https://github.com/microsoft/msquic/releases/tag/v2.5.10"
  }, {
    "type" : "WEB",
    "url" : "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62815"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-416" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-08T20:27:02Z",
    "nvd_published_at" : null
  }
}