{"schema_version":"1.9.0","id":"BIT-nats-2026-33248","published":"2026-03-27T17:45:26.680Z","modified":"2026-09-08T08:48:24.538774539Z","aliases":["CVE-2026-33248","GHSA-3f24-pcvm-5jqc","GO-2026-4828"],"summary":"NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching","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, when using mTLS for client identity, with `verify_and_map` to derive a NATS identity from the client certificate's Subject DN, certain patterns of RDN would not be correctly enforced, allowing for authentication bypass. This does require a valid certificate from a CA already trusted for client certificates, and `DN` naming patterns which the NATS maintainers consider highly unlikely. So this is an unlikely attack. Nonetheless, administrators who have been very sophisticated in their `DN` construction patterns might conceivably be impacted. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, developers should review their CA issuing practices.","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-2026-33248.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N"}]}],"references":[{"type":"ADVISORY","url":"https://advisories.nats.io/CVE/secnote-2026-13.txt"},{"type":"ADVISORY","url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-3f24-pcvm-5jqc"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33248"}],"database_specific":{"cpes":["cpe:2.3:a:nats:nats_server:*:*:*:*:*:go:*:*"],"severity":"Medium"}}