{"schema_version":"1.9.0","id":"CVE-2026-33248","published":"2026-03-25T20:18:28.923Z","modified":"2026-08-12T03:51:16.439533875Z","aliases":["BIT-nats-2026-33248","GHSA-3f24-pcvm-5jqc","GO-2026-4828"],"related":["CGA-mvv8-7788-xf2r","SUSE-SU-2026:1135-1","openSUSE-SU-2026:21483-1"],"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":[{"ranges":[{"type":"GIT","repo":"https://github.com/nats-io/nats-server","events":[{"introduced":"0"},{"fixed":"bef17e1d9de6574fae0eabe1798db0d4529834e4"},{"introduced":"fc6ec648d806652d282d2f0edb6cb9f22c895572"},{"fixed":"0e0639058e0d2d8fce0cc34941f9897da152ab32"}],"database_specific":{"cpe":"cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"2.11.15"},{"introduced":"2.12.0"},{"fixed":"2.12.6"}],"source":"CPE_RANGE"}}],"versions":["v2.12.4","v2.11.14","v2.12.5","v2.11.12","v2.12.5-RC.2","v2.12.5-RC.1","v2.11.12-RC.7","v2.12.4-RC.6","v2.11.12-RC.6","v2.12.4-RC.5","v2.11.12-RC.5","v2.12.4-RC.4","v2.12.2","v2.11.12-RC.4","v2.12.4-RC.3","v2.12.4-RC.2","v2.11.12-RC.3","v2.12.4-RC.1","v2.11.12-RC.2","v2.12.3","v2.11.12-RC.1","v2.11.11","v2.12.3-RC.5","v2.12.3-RC.4","v2.12.3-RC.3","v2.12.3-RC.2","v2.12.3-RC.1","v2.12.2-RC.4","v2.11.11-RC.4","v2.12.2-RC.3","v2.11.11-RC.3","v2.12.1","v2.12.2-RC.2","v2.11.11-RC.2","v2.11.11-RC.1","v2.12.2-RC.1","v2.11.10","v2.12.0","v2.12.1-RC.5","v2.12.1-RC.4","v2.12.1-RC.3","v2.12.1-RC.2","v2.12.1-RC.1","v2.11.10-RC.1","v2.11.9","v2.11.9-RC.3","v2.11.9-RC.2","v2.11.9-RC.1","v2.11.8","v2.11.8-RC.1","v2.11.7","v2.11.7-RC.3","v2.11.7-RC.2","v2.11.7-RC.1","v2.11.6","v2.11.6-RC.1","v2.11.5","v2.11.5-RC.4","v2.11.5-RC.3","v2.11.5-RC.2","v2.11.5-RC.1","v2.11.4","v2.11.4-RC.3","v2.11.4-RC.2","v2.11.4-RC.1","v2.11.3","v2.11.3-RC.2","v2.11.3-RC.1","v2.11.2","v2.11.2-RC.3","v2.11.2-RC.2","v2.11.2-RC.1","v2.11.0","v2.11.0-RC.5","v2.11.0-RC.4","v2.11.0-RC.3","v2.11.0-RC.2","v2.11.0-RC.1","v2.10.3","v2.10.2","v2.10.1","v2.10.0","v2.9.22","v2.9.21","v2.9.20","v2.9.19","v2.9.18","v2.9.17","v2.9.16","v2.9.15","v2.9.14","v2.9.12","v2.9.11","v2.9.10","v2.9.9","v2.9.8","v2.9.7","v2.9.6","v2.9.5","v2.9.4","v2.9.3","v2.9.2","v2.9.1","v2.9.0","v2.8.4","v2.8.3","v2.8.2","v2.8.1","v2.8.0","v2.7.4","v2.7.3","v2.7.2","v2.7.1","v2.7.0","v2.7.0-rc2","v2.7.0-rc1","v2.6.6","v2.6.5","v2.6.4","v2.6.3","v2.6.2","v2.6.1","v2.6.0","v2.5.0","v2.4.0","v2.3.4","v2.3.3","v2.3.2","v2.3.1","v2.3.0","v2.2.6","v2.2.5","v2.2.4","v2.2.3","v2.2.2","v2.2.1","v2.2.0","v2.1.7","v2.1.6","v2.1.4","v2.1.2","v2.1.0","v2.0.4","v2.0.2","v2.0.0","v2.0.0-RC19","v2.0.0-RC14","v1.3.0","v1.2.0","v1.1.0","v1.0.6","v1.0.4","v1.0.2","v1.0.0","v0.9.6","v0.9.4","v0.9.2","v0.8.1","v0.8.0","v0.7.2","v0.7.0","v0.6.8","v0.6.6","v0.6.4","v0.6.2","v0.6.0","v0.5.6","v0.5.4","v0.5.2","v0.5.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33248.json"}}],"references":[{"type":"ADVISORY","url":"https://advisories.nats.io/CVE/secnote-2026-13.txt"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33248.json"},{"type":"ADVISORY","url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-3f24-pcvm-5jqc"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33248"}],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-287","CWE-295"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-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"}]}