msrc_cve-2021-20197
Vulnerability from csaf_microsoft
Published
2021-03-02 00:00
Modified
2023-03-10 00:00
Summary
There is an open race window when writing output in the following utilities in GNU binutils version 2.35 and earlier:ar objcopy strip ranlib. When these utilities are run as a privileged user (presumably as part of a script updating binaries across different users) an unprivileged user can trick these utilities into getting ownership of arbitrary files through a symlink.

Notes

Additional Resources
To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle
Disclaimer
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.


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{
  "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-2021-20197 There is an open race window when writing output in the following utilities in GNU binutils version 2.35 and earlier:ar objcopy strip ranlib. When these utilities are run as a privileged user (presumably as part of a script updating binaries across different users) an unprivileged user can trick these utilities into getting ownership of arbitrary files through a symlink. - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-20197.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": "There is an open race window when writing output in the following utilities in GNU binutils version 2.35 and earlier:ar objcopy strip ranlib. When these utilities are run as a privileged user (presumably as part of a script updating binaries across different users) an unprivileged user can trick these utilities into getting ownership of arbitrary files through a symlink.",
    "tracking": {
      "current_release_date": "2023-03-10T00:00:00.000Z",
      "generator": {
        "date": "2025-10-19T21:50:22.129Z",
        "engine": {
          "name": "MSRC Generator",
          "version": "1.0"
        }
      },
      "id": "msrc_CVE-2021-20197",
      "initial_release_date": "2021-03-02T00:00:00.000Z",
      "revision_history": [
        {
          "date": "2021-04-02T00:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2023-03-10T00:00:00.000Z",
          "legacy_version": "1.1",
          "number": "2",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "2"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "\u003cazl3 crash 8.0.4-3",
                "product": {
                  "name": "\u003cazl3 crash 8.0.4-3",
                  "product_id": "2"
                }
              },
              {
                "category": "product_version",
                "name": "azl3 crash 8.0.4-3",
                "product": {
                  "name": "azl3 crash 8.0.4-3",
                  "product_id": "18344"
                }
              },
              {
                "category": "product_version_range",
                "name": "\u003cazl3 crash 8.0.4-4",
                "product": {
                  "name": "\u003cazl3 crash 8.0.4-4",
                  "product_id": "1"
                }
              },
              {
                "category": "product_version",
                "name": "azl3 crash 8.0.4-4",
                "product": {
                  "name": "azl3 crash 8.0.4-4",
                  "product_id": "18844"
                }
              }
            ],
            "category": "product_name",
            "name": "crash"
          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "\u003cazl3 crash 8.0.4-3 as a component of Azure Linux 3.0",
          "product_id": "17084-2"
        },
        "product_reference": "2",
        "relates_to_product_reference": "17084"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 crash 8.0.4-3 as a component of Azure Linux 3.0",
          "product_id": "18344-17084"
        },
        "product_reference": "18344",
        "relates_to_product_reference": "17084"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "\u003cazl3 crash 8.0.4-4 as a component of Azure Linux 3.0",
          "product_id": "17084-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17084"
      },
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 crash 8.0.4-4 as a component of Azure Linux 3.0",
          "product_id": "18844-17084"
        },
        "product_reference": "18844",
        "relates_to_product_reference": "17084"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2021-20197",
      "cwe": {
        "id": "CWE-59",
        "name": "Improper Link Resolution Before File Access (\u0026#39;Link Following\u0026#39;)"
      },
      "notes": [
        {
          "category": "general",
          "text": "redhat",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "fixed": [
          "18344-17084",
          "18844-17084"
        ],
        "known_affected": [
          "17084-2",
          "17084-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2021-20197 There is an open race window when writing output in the following utilities in GNU binutils version 2.35 and earlier:ar objcopy strip ranlib. When these utilities are run as a privileged user (presumably as part of a script updating binaries across different users) an unprivileged user can trick these utilities into getting ownership of arbitrary files through a symlink. - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-20197.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2021-04-02T00:00:00.000Z",
          "details": "8.0.4-4:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "17084-2",
            "17084-1"
          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "LOCAL",
            "availabilityImpact": "NONE",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "environmentalsScore": 0.0,
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "temporalScore": 6.3,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
          "products": [
            "17084-2",
            "17084-1"
          ]
        }
      ],
      "title": "There is an open race window when writing output in the following utilities in GNU binutils version 2.35 and earlier:ar objcopy strip ranlib. When these utilities are run as a privileged user (presumably as part of a script updating binaries across different users) an unprivileged user can trick these utilities into getting ownership of arbitrary files through a symlink."
    }
  ]
}


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