{"id":"ALPINE-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":"2026-09-18T17:30:03.617205111Z","published":"2026-05-20T10:16:26.530Z","upstream":["CVE-2026-33278"],"references":[{"type":"ADVISORY","url":"https://security.alpinelinux.org/vuln/CVE-2026-33278"}],"affected":[{"package":{"name":"unbound","ecosystem":"Alpine:v3.22","purl":"pkg:apk/alpine/unbound?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.19.1"},{"fixed":"1.25.2-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-33278.json"}},{"package":{"name":"unbound","ecosystem":"Alpine:v3.23","purl":"pkg:apk/alpine/unbound?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.19.1"},{"fixed":"1.25.2-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-33278.json"}},{"package":{"name":"unbound","ecosystem":"Alpine:v3.24","purl":"pkg:apk/alpine/unbound?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.19.1"},{"fixed":"1.25.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-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"}]}