{"id":"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":"2026-06-11T16:14:05.590835757Z","published":"2026-05-20T10:16:27.760Z","related":["ALSA-2026:23231","ALSA-2026:24365","ALSA-2026:24369","SUSE-SU-2026:21874-1","SUSE-SU-2026:21913-1","SUSE-SU-2026:2281-1","openSUSE-SU-2026:10903-1"],"references":[{"type":"ADVISORY","url":"https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42944.txt"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/nlnetlabs/unbound","events":[{"introduced":"919c8c9527281a7289415c00f8f2aed12b17a9aa"},{"fixed":"75b6dba593d4fff000434cd64807c6ebd50bd244"}],"database_specific":{"extracted_events":[{"introduced":"1.14.0"},{"fixed":"1.25.1"}],"cpe":"cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*","source":"CPE_RANGE"}}],"versions":["release-1.25.0","release-1.25.0rc1","release-1.24.0","release-1.24.0rc1","release-1.23.0rc1","release-1.22.0","release-1.22.0rc1","release-1.21.0","release-1.21.0rc1","release-1.20.0rc1","release-1.20.0","release-1.19.3rc1","release-1.19.0rc1","release-1.19.0","release-1.18.0","release-1.18.0rc1","release-1.16.2","release-1.16.1rc1","release-1.16.1","release-1.16.0rc1","release-1.16.0","release-1.15.0rc1","release-1.15.0","release-1.14.0rc1","release-1.14.0"],"database_specific":{"vanir_signatures_modified":"2026-06-02T08:21:51Z","source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-42944.json","vanir_signatures":[{"signature_type":"Function","id":"CVE-2026-42944-7cb89fac","signature_version":"v1","source":"https://github.com/nlnetlabs/unbound/commit/75b6dba593d4fff000434cd64807c6ebd50bd244","target":{"function":"rpz_callback_from_iterator_module","file":"services/rpz.c"},"deprecated":false,"digest":{"function_hash":"26148135886169857913239956572075736548","length":1502}},{"signature_type":"Line","id":"CVE-2026-42944-a3b17d2e","signature_version":"v1","source":"https://github.com/nlnetlabs/unbound/commit/75b6dba593d4fff000434cd64807c6ebd50bd244","target":{"file":"services/rpz.c"},"deprecated":false,"digest":{"line_hashes":["108481287081154918060659085654141150584","73953166938600086918224773195867549742","15251087855327528788980657535362970158","48532896601082718174781974683716349061","287248990686482337183326495344180868363","112058947495561481565691171486557666856","238258467286774268681997190612827183971","126648031849056156900266153546629664662","335401097143186200364020904286165936708","336096779053276656395004922884987906159","248876396313049466881138460638611830858","293135123655960925553682804594622081358","298612071867479354827766089224387452786","217265304546593372824910550975155656654","13292601781282786772501437491204364169","281286782737850123600796590480125479595","74511316679551775089931390035715335201","161066344018382590627892027575409612852","226343512543910522766563315515650712879"],"threshold":0.9}}]}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}