{"id":"ALPINE-CVE-2026-42944","details":"NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply packet. The relevant options ('nsid', 'answer-cookie', 'pad-responses' (default)) need to be enabled for the vulnerability to be exploited. An adversary who can query Unbound can exploit the vulnerability by attaching multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options to the query. A flaw in the size calculation of the EDNS field truncates the correct value which allows the encoder to overflow the available space when writing. Those two combined lead to a heap overflow write of Unbound controlled data and eventually a crash. Unbound 1.25.1 contains a patch with a fix to de-duplicate the EDNS options and a fix to prevent truncation of the EDNS field size calculation.","modified":"2026-09-18T17:30:02.301880381Z","published":"2026-05-20T10:16:27.760Z","upstream":["CVE-2026-42944"],"references":[{"type":"ADVISORY","url":"https://security.alpinelinux.org/vuln/CVE-2026-42944"}],"affected":[{"package":{"name":"unbound","ecosystem":"Alpine:v3.22","purl":"pkg:apk/alpine/unbound?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.14.0"},{"fixed":"1.25.2-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-42944.json"}},{"package":{"name":"unbound","ecosystem":"Alpine:v3.23","purl":"pkg:apk/alpine/unbound?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.14.0"},{"fixed":"1.25.2-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-42944.json"}},{"package":{"name":"unbound","ecosystem":"Alpine:v3.24","purl":"pkg:apk/alpine/unbound?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.14.0"},{"fixed":"1.25.1-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-42944.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:N/I:N/A:H"}]}