{"id":"CVE-2020-25685","state":"PUBLISHED","title":"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 t","description":"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.","publishedAt":"2021-01-20T00:00:00.000Z","updatedAt":"2025-11-04T19:12:13.209Z","severity":null,"assigner":"redhat","products":["n/a dnsmasq"],"affected":[{"vendor":"n/a","product":"dnsmasq","versions":[{"version":"dnsmasq 2.83","status":"affected"}]}],"references":["https://www.jsof-tech.com/disclosures/dnspooq/","https://bugzilla.redhat.com/show_bug.cgi?id=1889688","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/","https://security.gentoo.org/glsa/202101-17","https://www.debian.org/security/2021/dsa-4844","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/","https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61","https://www.kb.cert.org/vuls/id/434904"],"weaknesses":["CWE-326"],"ingestedAt":"2026-10-29T19:47:05.429Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2020/25xxx/CVE-2020-25685.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2020-25685","state":"PUBLISHED","datePublished":"2021-01-20T00:00:00.000Z","dateUpdated":"2025-11-04T19:12:13.209Z","assignerShortName":"redhat","assignerOrgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","dateReserved":"2020-09-16T00:00:00.000Z"},"containers":{"cna":{"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."}],"affected":[{"vendor":"n/a","product":"dnsmasq","versions":[{"version":"dnsmasq 2.83","status":"affected"}]}],"references":[{"url":"https://www.jsof-tech.com/disclosures/dnspooq/"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1889688"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/","name":"FEDORA-2021-84440e87ba","tags":["vendor-advisory"]},{"url":"https://security.gentoo.org/glsa/202101-17","name":"GLSA-202101-17","tags":["vendor-advisory"]},{"url":"https://www.debian.org/security/2021/dsa-4844","name":"DSA-4844","tags":["vendor-advisory"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/","name":"FEDORA-2021-2e4c3d5a9d","tags":["vendor-advisory"]},{"url":"https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-326","type":"CWE","lang":"en","description":"CWE-326"}]}],"providerMetadata":{"shortName":"redhat","orgId":"53f830b8-0a3f-465b-8143-3b8a9948e749","dateUpdated":"2022-10-07T00:00:00.000Z"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://www.jsof-tech.com/disclosures/dnspooq/","tags":["x_transferred"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=1889688","tags":["x_transferred"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/","name":"FEDORA-2021-84440e87ba","tags":["vendor-advisory","x_transferred"]},{"url":"https://security.gentoo.org/glsa/202101-17","name":"GLSA-202101-17","tags":["vendor-advisory","x_transferred"]},{"url":"https://www.debian.org/security/2021/dsa-4844","name":"DSA-4844","tags":["vendor-advisory","x_transferred"]},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/","name":"FEDORA-2021-2e4c3d5a9d","tags":["vendor-advisory","x_transferred"]},{"url":"https://www.arista.com/en/support/advisories-notices/security-advisories/12135-security-advisory-61","tags":["x_transferred"]},{"url":"https://www.kb.cert.org/vuls/id/434904"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-04T19:12:13.209Z"}}]}}}