{"cve":{"cve_id":"CVE-2026-84501","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":0.00742,"epss_percentile":0.53723,"epss_as_of":"2026-10-15","description":"An unauthenticated attacker can inject arbitrary fake log lines into Apache ZooKeeper's operational log by sending a crafted add_auth(\"ensemble\", ...) request containing newline characters (\\n). When the ensemble name doesn't match, EnsembleAuthenticationProvider.handleAuthentication() logs the raw, unsanitized name via LOG.warn(). Because SLF4J's {} placeholder preserves embedded newlines, the attacker can forge complete log entries — with arbitrary timestamps, log levels, class names, and messages — that are visually indistinguishable from genuine ZooKeeper log output.\n\nThis issue affects Apache ZooKeeper: from 3.9.0 through 3.9.5, from 3.8.0 through 3.8.6.\n\nUsers are recommended to upgrade to version 3.8.7 or 3.9.6, which fixes the issue.","published_at":"2026-09-16T09:28:10.294000Z","last_modified_at":"2026-09-18T14:36:51.747000Z","cvss_v3_score":5.3,"cvss_v3_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","cvss_v3_severity":"MEDIUM","cvss_v4_score":null,"cvss_v4_vector":null,"cvss_v4_severity":null,"ssvc_decision":null,"ssvc_exploitation":null,"ssvc_automatable":null,"ssvc_technical_impact":null,"cwes":["CWE-117"],"nvd_references":["https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33y"],"vuln_status":"Analyzed","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":"2026-09-16T11:03:42.089224Z","updated_at":"2026-09-20T12:41:36.173174Z"},"effective_severity":"MEDIUM","badges":[],"impact_analysis":[],"cvss_v3_decoded":{"version":"3.1","metrics":[{"metric":"AV","name":"Attack Vector","value":"N","value_label":"Network"},{"metric":"AC","name":"Attack Complexity","value":"L","value_label":"Low"},{"metric":"PR","name":"Privileges Required","value":"N","value_label":"None"},{"metric":"UI","name":"User Interaction","value":"N","value_label":"None"},{"metric":"S","name":"Scope","value":"U","value_label":"Unchanged"},{"metric":"C","name":"Confidentiality","value":"N","value_label":"None"},{"metric":"I","name":"Integrity","value":"L","value_label":"Low"},{"metric":"A","name":"Availability","value":"N","value_label":"None"}]},"cvss_v4_decoded":{"version":null,"metrics":[]},"affected":[{"vendor_slug":"apache","vendor_name":"apache","product_slug":"zookeeper","product_name":"zookeeper","version_start":"3.8.0","version_start_inclusive":true,"version_end":"3.8.7","version_end_inclusive":false,"cpe23_uri":"cpe:2.3:a:apache:zookeeper:*:*:*:*:*:*:*:*"},{"vendor_slug":"apache-software-foundation","vendor_name":"Apache Software Foundation","product_slug":"apache-zookeeper","product_name":"Apache ZooKeeper","version_start":"3.9.0","version_start_inclusive":true,"version_end":"3.9.5","version_end_inclusive":true,"cpe23_uri":"cve5:apache-software-foundation:apache-zookeeper:3.9.0:3.9.5"},{"vendor_slug":"apache-software-foundation","vendor_name":"Apache Software Foundation","product_slug":"apache-zookeeper","product_name":"Apache ZooKeeper","version_start":"3.8.0","version_start_inclusive":true,"version_end":"3.8.6","version_end_inclusive":true,"cpe23_uri":"cve5:apache-software-foundation:apache-zookeeper:3.8.0:3.8.6"}],"exploit_refs":[],"news":[],"references":[{"url":"https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33y","source_type":"MAILING_LIST","tags":["mailing-list"]}],"timeline":[{"type":"published","at":"2026-09-16T09:28:10.294000Z","label":"CVE published","source":null},{"type":"cvss_changed","at":"2026-09-16T21:03:42.088887Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-09-16T21:03:42.088887Z","label":"CVSS score revised","source":"cvelistv5"},{"type":"cvss_changed","at":"2026-09-16T21:03:42.088887Z","label":"CVSS score revised","source":"cvelistv5"}]}