{"schema_version":"1.9.0","id":"BIT-nats-2026-33219","published":"2026-03-27T17:45:18.190Z","modified":"2026-09-08T08:48:24.300401610Z","aliases":["CVE-2026-33219","GHSA-8r68-gvr4-jh7j","GO-2026-4831"],"summary":"NATS is vulnerable to pre-auth DoS through WebSockets client service","details":"NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, a malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-server before authentication; this requires sending a corresponding amount of data. This is a milder variant of CVE-2026-27571. That earlier issue was a compression bomb, this vulnerability is not. Attacks against this new issue thus require significant client bandwidth. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable websockets if not required for project deployment.","affected":[{"package":{"name":"nats","ecosystem":"Bitnami","purl":"pkg:bitnami/nats"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.11.15"},{"introduced":"2.12.0"},{"fixed":"2.12.6"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/nats/BIT-nats-2026-33219.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}],"references":[{"type":"ADVISORY","url":"https://advisories.nats.io/CVE/secnote-2026-02.txt"},{"type":"ADVISORY","url":"https://advisories.nats.io/CVE/secnote-2026-11.txt"},{"type":"ADVISORY","url":"https://github.com/advisories/GHSA-qrvq-68c2-7grw"},{"type":"ADVISORY","url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33219"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:21769"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:22347"},{"type":"WEB","url":"https://access.redhat.com/errata/RHSA-2026:23345"},{"type":"WEB","url":"https://access.redhat.com/security/cve/CVE-2026-33219"},{"type":"WEB","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2451445"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33219.json"}],"database_specific":{"cpes":["cpe:2.3:a:nats:nats_server:*:*:*:*:*:go:*:*"],"severity":"Medium"}}