{"id":"UBUNTU-CVE-2026-123594","details":"Hickory DNS hickory-proto through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1 before 0.26.2 contain an NSEC validation flaw that returns a secure proof for NXDOMAIN responses when the covering NSEC's Next Domain Name is a strict descendant of the query name, which actually proves the name exists as an empty non-terminal. On-path attackers can flip the unsigned rcode of a genuine signed NODATA response from NOERROR to NXDOMAIN, causing validators to accept forged nonexistence of the name.","modified":"2026-11-10T02:50:13.554033068Z","published":"2026-11-09T00:00:00Z","upstream":["CVE-2026-123594"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-123594"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-123594"},{"type":"REPORT","url":"https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-86vr-jm6c-7cpg"},{"type":"REPORT","url":"https://www.vulncheck.com/advisories/hickory-dns-through-0.26.0-alpha.1-dnssec-nsec-validation-bypass-for-empty-non-terminals"}],"affected":[{"package":{"name":"rust-hickory-proto","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/rust-hickory-proto?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.24.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"librust-hickory-proto-dev","binary_version":"0.24.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123594.json"}},{"package":{"name":"rust-hickory-net","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/rust-hickory-net?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.26.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"librust-hickory-net-dev","binary_version":"0.26.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123594.json"}},{"package":{"name":"rust-hickory-proto","ecosystem":"Ubuntu:26.10","purl":"pkg:deb/ubuntu/rust-hickory-proto?arch=source&distro=stonking"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.24.4-6","0.26.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"librust-hickory-proto-dev","binary_version":"0.26.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123594.json"}},{"package":{"name":"rust-hickory-proto","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/rust-hickory-proto?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.24.4-4.1","0.24.4-6"],"ecosystem_specific":{"binaries":[{"binary_name":"librust-hickory-proto-dev","binary_version":"0.24.4-6"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-123594.json"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N"},{"type":"Ubuntu","score":"medium"}]}