CVE-2020-25685 (GCVE-0-2020-25685)
Vulnerability from cvelistv5
Published
2021-01-20 00:00
Modified
2025-11-04 19:12
Severity ?
CWE
Summary
A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in forward.c:reply_query(), which is the forwarded query that matches the reply, by only using a weak hash of the query name. Due to the weak hash (CRC32 when dnsmasq is compiled without DNSSEC, SHA-1 when it is) this flaw allows an off-path attacker to find several different domains all having the same hash, substantially reducing the number of attempts they would have to perform to forge a reply and get it accepted by dnsmasq. This is in contrast with RFC5452, which specifies that the query name is one of the attributes of a query that must be used to match a reply. This flaw could be abused to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25684 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity.
References
Impacted products
Vendor Product Version
n/a dnsmasq Version: dnsmasq 2.83
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-04T19:12:13.209Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.jsof-tech.com/disclosures/dnspooq/"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1889688"
          },
          {
            "name": "FEDORA-2021-84440e87ba",
            "tags": [
              "vendor-advisory",
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/"
          },
          {
            "name": "GLSA-202101-17",
            "tags": [
              "vendor-advisory",
              "x_transferred"
            ],
            "url": "https://security.gentoo.org/glsa/202101-17"
          },
          {
            "name": "DSA-4844",
            "tags": [
              "vendor-advisory",
              "x_transferred"
            ],
            "url": "https://www.debian.org/security/2021/dsa-4844"
          },
          {
            "name": "FEDORA-2021-2e4c3d5a9d",
            "tags": [
              "vendor-advisory",
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61"
          },
          {
            "url": "https://www.kb.cert.org/vuls/id/434904"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "dnsmasq",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "dnsmasq 2.83"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "A flaw was found in dnsmasq before version 2.83. When getting a reply from a forwarded query, dnsmasq checks in forward.c:reply_query(), which is the forwarded query that matches the reply, by only using a weak hash of the query name. Due to the weak hash (CRC32 when dnsmasq is compiled without DNSSEC, SHA-1 when it is) this flaw allows an off-path attacker to find several different domains all having the same hash, substantially reducing the number of attempts they would have to perform to forge a reply and get it accepted by dnsmasq. This is in contrast with RFC5452, which specifies that the query name is one of the attributes of a query that must be used to match a reply. This flaw could be abused to perform a DNS Cache Poisoning attack. If chained with CVE-2020-25684 the attack complexity of a successful attack is reduced. The highest threat from this vulnerability is to data integrity."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-326",
              "description": "CWE-326",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2022-10-07T00:00:00.000Z",
        "orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
        "shortName": "redhat"
      },
      "references": [
        {
          "url": "https://www.jsof-tech.com/disclosures/dnspooq/"
        },
        {
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=1889688"
        },
        {
          "name": "FEDORA-2021-84440e87ba",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/"
        },
        {
          "name": "GLSA-202101-17",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://security.gentoo.org/glsa/202101-17"
        },
        {
          "name": "DSA-4844",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://www.debian.org/security/2021/dsa-4844"
        },
        {
          "name": "FEDORA-2021-2e4c3d5a9d",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/"
        },
        {
          "url": "https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61"
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
    "assignerShortName": "redhat",
    "cveId": "CVE-2020-25685",
    "datePublished": "2021-01-20T00:00:00.000Z",
    "dateReserved": "2020-09-16T00:00:00.000Z",
    "dateUpdated": "2025-11-04T19:12:13.209Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.