{"schema_version":"1.9.0","id":"GHSA-jxxm-27vp-c3m5","published":"2026-03-24T21:44:17Z","modified":"2026-09-10T03:51:00.416516974Z","aliases":["BIT-nats-2026-33217","CVE-2026-33217","GO-2026-4834"],"summary":"NATS allows MQTT clients to bypass ACL checks","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 provides an MQTT client interface.\n\n### Problem Description\n\nWhen using ACLs on message subjects, these ACLs were not applied in the `$MQTT.>` namespace, allowing MQTT clients to bypass ACL checks for MQTT subjects.\n\n### Affected Versions\n\nAny version before v2.12.6 or v2.11.15\n\n### Workarounds\n\nNone.","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-jxxm-27vp-c3m5/GHSA-jxxm-27vp-c3m5.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-jxxm-27vp-c3m5/GHSA-jxxm-27vp-c3m5.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-jxxm-27vp-c3m5/GHSA-jxxm-27vp-c3m5.json"}}],"references":[{"type":"WEB","url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-jxxm-27vp-c3m5"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33217"},{"type":"WEB","url":"https://advisories.nats.io/CVE/secnote-2026-07.txt"},{"type":"PACKAGE","url":"https://github.com/nats-io/nats-server"}],"database_specific":{"cwe_ids":["CWE-863"],"github_reviewed":true,"github_reviewed_at":"2026-03-24T21:44:17Z","nvd_published_at":"2026-03-25T20:16:32Z","severity":"HIGH"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N"}]}