{"id":"CVE-2026-32665","details":"In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, when downstream DNS-over-QUIC (DoQ) is enabled, the first two bidirectional streams on a new QUIC connection (stream_id 0 and 4) bypass the per-stream 'quic-size' gate entirely, and large input buffers are allocated later, after only the 2-byte length prefix has been received from the initial streams. As a result, a remote client can make Unbound exceed the configured 'quic-size' limit with low-cost input. Using only one connection and two streams, each sending a declared 65535-byte length prefix and then holding the streams open, a client can already trivially make Unbound roughly allocate double that amount. This is a remote availability issue / memory-accounting bypass in the downstream DoQ implementation that leads to denial of service for new DoQ clients. This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces.","modified":"2026-07-27T14:06:40.977099Z","published":"2026-07-22T14:17:18.193Z","related":["openSUSE-SU-2026:11380-1"],"references":[{"type":"ADVISORY","url":"https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-32665.txt"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/nlnetlabs/unbound","events":[{"introduced":"0076736fc40298eb6252705e6e158462c6b24d06"},{"fixed":"c33ad1b1a21e48bfe4f140e90252a9be1b0c5745"}],"database_specific":{"source":"CPE_RANGE","cpe":"cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"1.22.0"},{"fixed":"1.25.2"}]}}],"versions":["release-1.25.1","release-1.25.0","release-1.25.0rc1","release-1.24.0","release-1.24.0rc1","release-1.23.0rc1","release-1.22.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-32665.json"}}],"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"}]}