MSRC_CVE-2021-32066

Vulnerability from csaf_microsoft - Published: 2021-08-02 00:00 - Updated: 2021-12-16 00:00
Summary
An issue was discovered in Ruby through 2.6.7 2.7.x through 2.7.3 and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command aka a "StartTLS stripping attack."

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/"
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    "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-2021-32066 An issue was discovered in Ruby through 2.6.7 2.7.x through 2.7.3 and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command aka a \"StartTLS stripping attack.\" - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-32066.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": "An issue was discovered in Ruby through 2.6.7 2.7.x through 2.7.3 and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command aka a \"StartTLS stripping attack.\"",
    "tracking": {
      "current_release_date": "2021-12-16T00:00:00.000Z",
      "generator": {
        "date": "2025-10-19T22:09:27.537Z",
        "engine": {
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          "version": "1.0"
        }
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      "initial_release_date": "2021-08-02T00:00:00.000Z",
      "revision_history": [
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          "date": "2021-08-11T00:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2021-12-16T00:00:00.000Z",
          "legacy_version": "1.1",
          "number": "2",
          "summary": "Added ruby to CBL-Mariner 2.0"
        }
      ],
      "status": "final",
      "version": "2"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "1.0",
                "product": {
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            ],
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            "branches": [
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  "vulnerabilities": [
    {
      "cve": "CVE-2021-32066",
      "cwe": {
        "id": "CWE-755",
        "name": "Improper Handling of Exceptional Conditions"
      },
      "notes": [
        {
          "category": "general",
          "text": "mitre",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
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          "17086-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2021-32066 An issue was discovered in Ruby through 2.6.7 2.7.x through 2.7.3 and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command aka a \"StartTLS stripping attack.\" - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2021-32066.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2021-08-11T00:00:00.000Z",
          "details": "2.6.7-2:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "product_ids": [
            "16820-2"
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          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
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          "product_ids": [
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          ],
          "url": "https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade"
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 7.4,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "environmentalsScore": 0.0,
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "temporalScore": 7.4,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
            "version": "3.1"
          },
          "products": [
            "16820-2",
            "17086-1"
          ]
        }
      ],
      "title": "An issue was discovered in Ruby through 2.6.7 2.7.x through 2.7.3 and 3.x through 3.0.1. Net::IMAP does not raise an exception when StartTLS fails with an an unknown response which might allow man-in-the-middle attackers to bypass the TLS protections by leveraging a network position between the client and the registry to block the StartTLS command aka a \"StartTLS stripping attack.\""
    }
  ]
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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