{
  "document": {
    "category": "csaf_vex",
    "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"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2021-3418 If certificates that signed grub are installed into db grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown yet it could have been tampered. This flaw is a reintroduction of CVE-2020-15705 and only affects grub2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism. - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-3418.json"
      },
      {
        "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": "If certificates that signed grub are installed into db grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown yet it could have been tampered. This flaw is a reintroduction of CVE-2020-15705 and only affects grub2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism.",
    "tracking": {
      "current_release_date": "2021-12-16T00:00:00.000Z",
      "generator": {
        "date": "2025-10-19T21:50:22.137Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2021-3418",
      "initial_release_date": "2021-03-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2021-03-23T00:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2021-12-16T00:00:00.000Z",
          "legacy_version": "1.1",
          "number": "2",
          "summary": "Added grub2 to CBL-Mariner 2.0"
        }
      ],
      "status": "final",
      "version": "2"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "2.0",
                "product": {
                  "name": "CBL Mariner 2.0",
                  "product_id": "17086"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003ccbl2 grub2 2.06~rc1-7",
                "product": {
                  "name": "\u003ccbl2 grub2 2.06~rc1-7",
                  "product_id": "1"
                }
              },
              {
                "category": "product_version",
                "name": "cbl2 grub2 2.06~rc1-7",
                "product": {
                  "name": "cbl2 grub2 2.06~rc1-7",
                  "product_id": "19072"
                }
              }
            ],
            "category": "product_name",
            "name": "grub2"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "\u003ccbl2 grub2 2.06~rc1-7 as a component of CBL Mariner 2.0",
          "product_id": "17086-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17086"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "cbl2 grub2 2.06~rc1-7 as a component of CBL Mariner 2.0",
          "product_id": "19072-17086"
        },
        "product_reference": "19072",
        "relates_to_product_reference": "17086"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2021-3418",
      "cwe": {
        "id": "CWE-281",
        "name": "Improper Preservation of Permissions"
      },
      "notes": [
        {
          "category": "general",
          "text": "redhat",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "fixed": [
          "19072-17086"
        ],
        "known_affected": [
          "17086-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2021-3418 If certificates that signed grub are installed into db grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown yet it could have been tampered. This flaw is a reintroduction of CVE-2020-15705 and only affects grub2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism. - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-3418.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2021-03-23T00:00:00.000Z",
          "details": "2.06~rc1-7:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "17086-1"
          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "LOCAL",
            "availabilityImpact": "HIGH",
            "baseScore": 6.4,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "environmentalsScore": 0.0,
            "integrityImpact": "HIGH",
            "privilegesRequired": "HIGH",
            "scope": "UNCHANGED",
            "temporalScore": 6.4,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "products": [
            "17086-1"
          ]
        }
      ],
      "title": "If certificates that signed grub are installed into db grub can be booted directly. It will then boot any kernel without signature validation. The booted kernel will think it was booted in secureboot mode and will implement lockdown yet it could have been tampered. This flaw is a reintroduction of CVE-2020-15705 and only affects grub2 versions prior to 2.06 and upstream and distributions using the shim_lock mechanism."
    }
  ]
}