MSRC_CVE-2020-25684

Vulnerability from csaf_microsoft - Published: 2021-01-02 00:00 - Updated: 2021-01-29 00:00
Summary
A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However it does not use the address/port to retrieve the exact forwarded query substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452 which specifies a query's attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.

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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    "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": {
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      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2020-25684 A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However it does not use the address/port to retrieve the exact forwarded query substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452 which specifies a query\u0027s attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity. - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2020-25684.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
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      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However it does not use the address/port to retrieve the exact forwarded query substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452 which specifies a query\u0027s attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.",
    "tracking": {
      "current_release_date": "2021-01-29T00:00:00.000Z",
      "generator": {
        "date": "2025-10-19T21:39:52.588Z",
        "engine": {
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        }
      },
      "id": "msrc_CVE-2020-25684",
      "initial_release_date": "2021-01-02T00:00:00.000Z",
      "revision_history": [
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          "date": "2021-01-29T00:00:00.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        }
      ],
      "status": "final",
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    }
  },
  "product_tree": {
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        ],
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    "relationships": [
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        "category": "default_component_of",
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  "vulnerabilities": [
    {
      "cve": "CVE-2020-25684",
      "cwe": {
        "id": "CWE-358",
        "name": "Improperly Implemented Security Check for Standard"
      },
      "notes": [
        {
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          "text": "redhat",
          "title": "Assigning CNA"
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        "known_affected": [
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      "references": [
        {
          "category": "self",
          "summary": "CVE-2020-25684 A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However it does not use the address/port to retrieve the exact forwarded query substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452 which specifies a query\u0027s attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity. - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2021/msrc_cve-2020-25684.json"
        }
      ],
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2021-01-29T00:00:00.000Z",
          "details": "2.85-1:Security Update:https://learn.microsoft.com/en-us/azure/azure-linux/tutorial-azure-linux-upgrade",
          "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": 3.7,
            "baseSeverity": "LOW",
            "confidentialityImpact": "NONE",
            "environmentalsScore": 0.0,
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "temporalScore": 3.7,
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
            "version": "3.1"
          },
          "products": [
            "16820-1"
          ]
        }
      ],
      "title": "A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query dnsmasq checks in the forward.c:reply_query() if the reply destination address/port is used by the pending forwarded queries. However it does not use the address/port to retrieve the exact forwarded query substantially reducing the number of attempts an attacker on the network would have to perform to forge a reply and get it accepted by dnsmasq. This issue contrasts with RFC5452 which specifies a query\u0027s attributes that all must be used to match a reply. This flaw allows an attacker to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25685 or CVE-2020-25686 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity."
    }
  ]
}


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