CVE-2020-25687
A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 89.3%, higher than 100% of all known CVEs. Patch or mitigate before the next change window.
Description
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.
- CVSS 3.1
- 5.9 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 89.28% probability · 100th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-122
- Affected
- thekelleys/dnsmasq · fedoraproject/fedora · debian/debian linux
- Source
- secalert@redhat.com
EPSS moved from 89.3% on 22 October 2026 to 89.3% on 3 November 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
References
- https://bugzilla.redhat.com/show_bug.cgi?id=1891568Issue 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=1891568Issue 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.