{"id":"DEBIAN-CVE-2026-33278","details":"NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.","modified":"2026-09-01T16:06:39.510176149Z","published":"2026-05-20T10:16:26.530Z","upstream":["CVE-2026-33278"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-33278"}],"affected":[{"package":{"name":"unbound","ecosystem":"Debian:12","purl":"pkg:deb/debian/unbound?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.17.1-2","1.17.1-2+deb12u1","1.17.1-2+deb12u2","1.17.1-2+deb12u3","1.17.1-2+deb12u4","1.17.1-2+loong64","1.18.0-1","1.18.0-2","1.19.1-1","1.19.2-1","1.20.0-1","1.21.1-1","1.22.0-1","1.22.0-2","1.23.1-1","1.24.0-1","1.24.0-2","1.24.1-1","1.24.1-2","1.24.2-1","1.25.0-1","1.25.1-1","1.25.2-1","1.26.0-1","1.26.0-2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33278.json"}},{"package":{"name":"unbound","ecosystem":"Debian:13","purl":"pkg:deb/debian/unbound?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.22.0-2+deb13u3"}]}],"versions":["1.22.0-2","1.22.0-2+deb13u1","1.22.0-2+deb13u2"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33278.json"}},{"package":{"name":"unbound","ecosystem":"Debian:14","purl":"pkg:deb/debian/unbound?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.25.1-1"}]}],"versions":["1.22.0-2","1.23.1-1","1.24.0-1","1.24.0-2","1.24.1-1","1.24.1-2","1.24.2-1","1.25.0-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33278.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}