ubuntu-cve-2020-25687
Vulnerability from osv_ubuntu
Published
2021-01-19 00:00
Modified
2025-08-11 04:41
Summary
Details

A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

Severity
5.9 (Medium)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "dnsmasq",
            "binary_version": "2.75-1ubuntu0.16.04.7"
          },
          {
            "binary_name": "dnsmasq-base",
            "binary_version": "2.75-1ubuntu0.16.04.7"
          },
          {
            "binary_name": "dnsmasq-utils",
            "binary_version": "2.75-1ubuntu0.16.04.7"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:16.04:LTS",
        "name": "dnsmasq",
        "purl": "pkg:deb/ubuntu/dnsmasq@2.75-1ubuntu0.16.04.7?arch=source\u0026distro=xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.75-1ubuntu0.16.04.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.75-1",
        "2.75-1ubuntu0.16.04.1",
        "2.75-1ubuntu0.16.04.2",
        "2.75-1ubuntu0.16.04.3",
        "2.75-1ubuntu0.16.04.4",
        "2.75-1ubuntu0.16.04.5"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "dnsmasq",
            "binary_version": "2.79-1ubuntu0.2"
          },
          {
            "binary_name": "dnsmasq-base",
            "binary_version": "2.79-1ubuntu0.2"
          },
          {
            "binary_name": "dnsmasq-base-lua",
            "binary_version": "2.79-1ubuntu0.2"
          },
          {
            "binary_name": "dnsmasq-utils",
            "binary_version": "2.79-1ubuntu0.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "dnsmasq",
        "purl": "pkg:deb/ubuntu/dnsmasq@2.79-1ubuntu0.2?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.79-1ubuntu0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.78-1",
        "2.78-3",
        "2.79-1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "dnsmasq",
            "binary_version": "2.80-1.1ubuntu1.2"
          },
          {
            "binary_name": "dnsmasq-base",
            "binary_version": "2.80-1.1ubuntu1.2"
          },
          {
            "binary_name": "dnsmasq-base-lua",
            "binary_version": "2.80-1.1ubuntu1.2"
          },
          {
            "binary_name": "dnsmasq-utils",
            "binary_version": "2.80-1.1ubuntu1.2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "dnsmasq",
        "purl": "pkg:deb/ubuntu/dnsmasq@2.80-1.1ubuntu1.2?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.80-1.1ubuntu1.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.80-1ubuntu2",
        "2.80-1ubuntu4",
        "2.80-1.1ubuntu1"
      ]
    }
  ],
  "aliases": [],
  "details": "A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.",
  "id": "UBUNTU-CVE-2020-25687",
  "modified": "2025-08-11T04:41:27Z",
  "published": "2021-01-19T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2020-25687"
    },
    {
      "type": "REPORT",
      "url": "https://www.jsof-tech.com/disclosures/dnspooq/"
    },
    {
      "type": "REPORT",
      "url": "http://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q1/014599.html"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-4698-1"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2020-25687"
    }
  ],
  "related": [
    "USN-4698-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2020-25687"
  ]
}



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