CVE-2020-25683

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. A remote attacker, who can create valid DNS replies, could use this flaw 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 get_rdata() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

• CWE-122

• https://bugzilla.redhat.com/show_bug.cgi?id=1882018Issue Tracking, Patch, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/03/msg00027.htmlMailing List, Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
• https://security.gentoo.org/glsa/202101-17Third Party Advisory
• https://www.debian.org/security/2021/dsa-4844Third Party Advisory
• https://www.jsof-tech.com/disclosures/dnspooq/Third Party Advisory
• https://bugzilla.redhat.com/show_bug.cgi?id=1882018Issue Tracking, Patch, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/03/msg00027.htmlMailing List, Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
• https://security.gentoo.org/glsa/202101-17Third Party Advisory
• https://www.debian.org/security/2021/dsa-4844Third Party Advisory
• https://www.jsof-tech.com/disclosures/dnspooq/Third Party Advisory
• https://www.kb.cert.org/vuls/id/434904

Published

Jan 20, 2021

Last Modified

Jun 17, 2026

Status

Modified

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