GHSA-W5F4-FX9M-M4Q7

Vulnerability from github – Published: 2026-10-06 15:33 – Updated: 2026-10-06 15:33
VLAI
Summary
MsQuic: Improper Certificate Validation in Microsoft.Native.Quic.MsQuic.OpenSSL
Details

Summary

Improper TLS hostname verification allows a man-in-the-middle (MITM) attack on MsQuic.

Details

Only MsQuic with the OpenSSL and QuicTLS TLS backends is affected (the Schannel backend is not affected).

Patches

2.6.1, 2.5.11, and 2.4.20

Impact

An on-path attacker could spoof a server identity by using a certificate that doesn't match the intended target server hostname.

Severity
9.1 (Critical)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Microsoft.Native.Quic.MsQuic.OpenSSL"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.4.20"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Microsoft.Native.Quic.MsQuic.OpenSSL"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.5.0"
            },
            {
              "fixed": "2.5.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "NuGet",
        "name": "Microsoft.Native.Quic.MsQuic.OpenSSL"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.0"
            },
            {
              "fixed": "2.6.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-105794"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-06T15:33:08Z",
    "nvd_published_at": "2026-10-06T15:17:16Z",
    "severity": "CRITICAL"
  },
  "details": "# Summary\n\nImproper TLS hostname verification allows a man-in-the-middle (MITM) attack on MsQuic. \n\n# Details\n\nOnly MsQuic with the OpenSSL and QuicTLS TLS backends is affected (the Schannel backend is not affected).\n\n## Patches\n\n2.6.1, 2.5.11, and 2.4.20\n\n# Impact\n\nAn on-path attacker could spoof a server identity by using a certificate that doesn\u0027t match the intended target server hostname.",
  "id": "GHSA-w5f4-fx9m-m4q7",
  "modified": "2026-10-06T15:33:08Z",
  "published": "2026-10-06T15:33:08Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/security/advisories/GHSA-w5f4-fx9m-m4q7"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-105794"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/pull/6274"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/pull/6275"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/pull/6276"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/pull/6277"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/commit/0591586443cc73a2d2cfb679527d91a144b4a412"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/commit/508e811370df93e2ad848f5c78347d4fe4f65a91"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/commit/90fd45498bf9b506b8556fb407088688474d6c81"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/commit/a01333cf7c2659cce0ff03ef3f21e1ff15bb5b83"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/microsoft/msquic"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/releases/tag/v2.4.20"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/releases/tag/v2.5.11"
    },
    {
      "type": "WEB",
      "url": "https://github.com/microsoft/msquic/releases/tag/v2.6.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "MsQuic: Improper Certificate Validation in Microsoft.Native.Quic.MsQuic.OpenSSL"
}



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