{"schema_version": "1.6.1", "id": "CVE-2026-84501", "summary": "Operational log forgery via newline injection in EnsembleAuthenticationProvider", "details": "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.", "affected": [{"ranges": [{"type": "SEMVER", "events": [{"introduced": "3.9.0"}, {"last_affected": "3.9.0"}]}, {"type": "SEMVER", "events": [{"introduced": "3.8.0"}, {"last_affected": "3.8.0"}]}]}], "references": [{"type": "WEB", "url": "https://lists.apache.org/thread/ohby1g6zjt72p0w79rhbr41nczzvr33y"}]}