{"id":5071,"date":"2026-09-04T18:46:58","date_gmt":"2026-09-04T10:46:58","guid":{"rendered":"https:\/\/www.54iter.cn\/?vuln=cve-2026-5856"},"modified":"2026-09-04T18:46:58","modified_gmt":"2026-09-04T10:46:58","slug":"cve-2026-5856","status":"publish","type":"vuln","link":"https:\/\/www.54iter.cn\/?vuln=cve-2026-5856","title":{"rendered":"CVE-2026-5856 [HIGH] &#8211; Contiki-NG&#8217;s DNS\/mDNS resolver skip_name() in os\/services\/resolv\/resolv.c walks DNS wire-f"},"content":{"rendered":"<p>Contiki-NG&#8217;s DNS\/mDNS resolver skip_name() in os\/services\/resolv\/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata() invokes it in a loop iterating nquestions times from the attacker-controlled DNS header before validating the transaction ID. An attacker who sets nquestions higher than the number of complete questions present causes skip_name() to walk past the UDP packet buffer, and the returned pointer is cast to struct dns_answer * for further memory reads. On builds with RESOLV_CONF_SUPPORTS_MDNS enabled, any peer on the local segment can trigger the read unauthenticated via a multicast UDP 5353 packet with no outstanding query required; on standard DNS builds an attacker who can inject a UDP response from port 53 during an outstanding query can trigger the same read. Impact is out-of-bounds read of uip_buf and adjacent memory, disclosing memory contents or crashing the resolver.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Contiki-NG&#8217;s DNS\/mDNS resolver skip_name() in os\/services\/resolv\/resolv.c walks DNS wire-format name labels with no packet-boundary check, and the caller in newdata() invokes it in a loop iterating nq<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-5071","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/5071","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5071"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5071"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5071"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}