{
  "document": {
    "acknowledgments": [
      {
        "names": [
          "Kugelblitz with Microsoft"
        ]
      },
      {
        "names": [
          "Kugelblitz with Microsoft"
        ]
      }
    ],
    "aggregate_severity": {
      "namespace": "https://www.microsoft.com/en-us/msrc/security-update-severity-rating-system",
      "text": "Important"
    },
    "category": "csaf_security_advisory",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      },
      {
        "category": "general",
        "text": "Required. The vulnerability documented by this CVE requires customer action to resolve.",
        "title": "Customer Action"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2026-66311 Microsoft Edge (Chromium-based) Tampering Vulnerability - HTML",
        "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66311"
      },
      {
        "category": "self",
        "summary": "CVE-2026-66311 Microsoft Edge (Chromium-based) Tampering Vulnerability - CSAF",
        "url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-66311.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Exploitability Index",
        "url": "https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "Microsoft Edge (Chromium-based) Tampering Vulnerability",
    "tracking": {
      "current_release_date": "2026-07-31T07:00:00.000Z",
      "generator": {
        "date": "2026-08-01T01:13:40.265Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2026-66311",
      "initial_release_date": "2026-07-31T07:00:00.000Z",
      "revision_history": [
        {
          "date": "2026-07-31T07:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "1"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "category": "product_version_range",
            "name": "<151.0.4129.59",
            "product": {
              "name": "Microsoft Edge (Chromium-based) <151.0.4129.59",
              "product_id": "1"
            }
          },
          {
            "category": "product_version",
            "name": "151.0.4129.59",
            "product": {
              "name": "Microsoft Edge (Chromium-based) 151.0.4129.59",
              "product_id": "11655"
            }
          }
        ],
        "category": "product_name",
        "name": "Microsoft Edge (Chromium-based)"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-66311",
      "cwe": {
        "id": "CWE-862",
        "name": "Missing Authorization"
      },
      "notes": [
        {
          "category": "general",
          "text": "Microsoft",
          "title": "Assigning CNA"
        },
        {
          "category": "faq",
          "text": "An attacker who successfully exploits this vulnerability cannot modify any sensitive user data or cause user data to become unavailable but can access sensitive user data.",
          "title": "According to the CVSS metrics, successful exploitation of this vulnerability could lead to major loss of confidentiality (C:H), but lead to no loss of integrity (I:N) or availability (A:N). What does that mean for this vulnerability?"
        },
        {
          "category": "faq",
          "text": "151.0.4129.59: 151.0.4129.59, 07/31/2026: 07/31/2026, 151.0.7922.71/.72: 151.0.7922.71/.72",
          "title": "What is the version information for this release?"
        }
      ],
      "product_status": {
        "fixed": [
          "11655"
        ],
        "known_affected": [
          "1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-66311 Microsoft Edge (Chromium-based) Tampering Vulnerability - HTML",
          "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66311"
        },
        {
          "category": "self",
          "summary": "CVE-2026-66311 Microsoft Edge (Chromium-based) Tampering Vulnerability - CSAF",
          "url": "https://msrc.microsoft.com/csaf/advisories/2026/msrc_cve-2026-66311.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2026-07-31T07:00:00.000Z",
          "details": "151.0.4129.59:Security Update:https://docs.microsoft.com/en-us/DeployEdge/microsoft-edge-relnotes-security",
          "product_ids": [
            "1"
          ],
          "url": "https://docs.microsoft.com/en-us/DeployEdge/microsoft-edge-relnotes-security"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "NONE",
            "baseScore": 6.2,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "environmentalScore": 0.0,
            "exploitCodeMaturity": "UNPROVEN",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "remediationLevel": "OFFICIAL_FIX",
            "reportConfidence": "CONFIRMED",
            "scope": "UNCHANGED",
            "temporalScore": 5.4,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C",
            "version": "3.1"
          },
          "products": [
            "1"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Tampering"
        },
        {
          "category": "exploit_status",
          "details": "Publicly Disclosed:No;Exploited:No;Latest Software Release:Exploitation Unlikely"
        }
      ],
      "title": "Microsoft Edge (Chromium-based) Tampering Vulnerability"
    }
  ]
}