{"cve":{"cve_id":"CVE-2026-33278","is_kev":false,"kev_date_added":null,"kev_vendor_project":null,"kev_product":null,"kev_vulnerability_name":null,"kev_short_description":null,"kev_required_action":null,"kev_due_date":null,"kev_known_ransomware":null,"kev_notes":null,"kev_cwes":null,"epss_score":0.00888,"epss_percentile":0.54594,"epss_as_of":"2026-06-23","description":"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.","published_at":"2026-05-20T09:18:15.225000Z","last_modified_at":null,"cvss_v3_score":null,"cvss_v3_vector":null,"cvss_v3_severity":null,"cvss_v4_score":9.1,"cvss_v4_vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/U:Red","cvss_v4_severity":"CRITICAL","ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-416","CWE-672"],"nvd_references":["https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txt"],"vuln_status":null,"trending_score":null,"is_trending":false,"has_trended":false,"trended_number_one":false,"trending_peak_score":null,"trending_peak_rank":null,"started_trending_at":null,"trended_number_one_at":null,"summary_generated":null,"summary_generated_at":null,"summary_model":null,"created_at":"2026-06-24T00:09:39.878444Z","updated_at":"2026-06-28T23:29:53.161929Z"},"effective_severity":"CRITICAL","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":null,"metrics":[]},"cvss_v4_decoded":{"version":"4.0","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"AT","name":"Attack Requirements","value":"N","value_label":"None"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"VC","name":"Confidentiality (Vulnerable System)","value":"H","value_label":"High"},{"metric":"VI","name":"Integrity (Vulnerable System)","value":"H","value_label":"High"},{"metric":"VA","name":"Availability (Vulnerable System)","value":"H","value_label":"High"},{"metric":"SC","name":"Confidentiality (Subsequent System)","value":"H","value_label":"High"},{"metric":"SI","name":"Integrity (Subsequent System)","value":"H","value_label":"High"},{"metric":"SA","name":"Availability (Subsequent System)","value":"H","value_label":"High"},{"metric":"E","name":"E","value":"U","value_label":"Unchanged"},{"metric":"U","name":"U","value":"Red","value_label":"Red"}]},"affected":[{"vendor_slug":"nlnet-labs","vendor_name":"NLnet Labs","product_slug":"unbound","product_name":"Unbound","version_start":"1.19.1","version_start_inclusive":true,"version_end":"1.25.1","version_end_inclusive":false,"cpe23_uri":"cve5:nlnet-labs:unbound:1.19.1:1.25.1"}],"exploit_refs":[],"news":[],"references":[{"url":"https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txt","source_type":"MISC","tags":[]}],"timeline":[{"type":"published","at":"2026-05-20T09:18:15.225000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-06-28T17:53:15.351162Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:53:15.351162Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-06-28T17:53:15.351162Z","label":"CVSS score revised","source":"cvelistv5"}]}