{"schema_version":"1.7.5","id":"GHSA-vprv-35vv-q339","published":"2026-03-24T21:45:29Z","modified":"2026-03-27T22:18:40.857350Z","aliases":["BIT-nats-2026-33218","CVE-2026-33218","GO-2026-4837"],"related":["CGA-32mq-856x-9662"],"summary":"NATS has pre-auth server panic via leafnode handling","details":"### Background\n\nNATS.io is a high performance open source pub-sub distributed communication technology, built for the cloud, on-premise, IoT, and edge computing.\n\nThe nats-server allows hub/spoke topologies using \"leafnode\" connections by other nats-servers.\n\n### Problem Description\n\nA client which can connect to the leafnode port can crash the nats-server with a certain malformed message pre-authentication.\n\n### Affected Versions\n\nAny version before v2.12.6 or v2.11.15\n\n### Workarounds\n\n1. Disable leafnode support if not needed.\n2. Restrict network connections to your leafnode port, if plausible without compromising the service offered.\n\n### References\n\n * This document is canonically: <https://advisories.nats.io/CVE/secnote-2026-10.txt>\n * GHSA advisory: <https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339>\n * MITRE CVE entry: <https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-33218>","affected":[{"package":{"name":"github.com/nats-io/nats-server/v2","ecosystem":"Go","purl":"pkg:golang/github.com/nats-io/nats-server/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.11.15"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-vprv-35vv-q339/GHSA-vprv-35vv-q339.json"}},{"package":{"name":"github.com/nats-io/nats-server/v2","ecosystem":"Go","purl":"pkg:golang/github.com/nats-io/nats-server/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.12.0-RC.1"},{"fixed":"2.12.6"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-vprv-35vv-q339/GHSA-vprv-35vv-q339.json"}},{"package":{"name":"github.com/nats-io/nats-server","ecosystem":"Go","purl":"pkg:golang/github.com/nats-io/nats-server"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-vprv-35vv-q339/GHSA-vprv-35vv-q339.json"}}],"references":[{"type":"WEB","url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33218"},{"type":"WEB","url":"https://advisories.nats.io/CVE/secnote-2026-10.txt"},{"type":"PACKAGE","url":"https://github.com/nats-io/nats-server"}],"database_specific":{"cwe_ids":["CWE-20"],"github_reviewed":true,"github_reviewed_at":"2026-03-24T21:45:29Z","nvd_published_at":"2026-03-25T20:16:32Z","severity":"HIGH"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}