{"schema_version":"1.7.5","id":"GHSA-3f24-pcvm-5jqc","published":"2026-03-24T21:51:08Z","modified":"2026-03-27T22:16:25.848943Z","aliases":["BIT-nats-2026-33248","CVE-2026-33248","GO-2026-4828"],"related":["CGA-mvv8-7788-xf2r"],"summary":"NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching","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\nOne authentication model supported is mTLS, deriving the NATS client identity from properties of the TLS Client Certificate.\n\n### Problem Description\n\nWhen 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.\n\nThis does require a valid certificate from a CA already trusted for client certificates, and `DN` naming patterns which the NATS maintainers consider highly unlikely.\n\nSo this is an unlikely attack. Nonetheless, administrators who have been very sophisticated in their `DN` construction patterns might conceivably be impacted.\n\n### Affected Versions\n\nFixed in nats-server 2.12.6 & 2.11.15\n\n### Workarounds\n\nDevelopers should review their CA issuing practices.","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-3f24-pcvm-5jqc/GHSA-3f24-pcvm-5jqc.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-3f24-pcvm-5jqc/GHSA-3f24-pcvm-5jqc.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-3f24-pcvm-5jqc/GHSA-3f24-pcvm-5jqc.json"}}],"references":[{"type":"WEB","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"},{"type":"WEB","url":"https://advisories.nats.io/CVE/secnote-2026-13.txt"},{"type":"PACKAGE","url":"https://github.com/nats-io/nats-server"}],"database_specific":{"cwe_ids":["CWE-287","CWE-295"],"github_reviewed":true,"github_reviewed_at":"2026-03-24T21:51:08Z","nvd_published_at":"2026-03-25T21:16:47Z","severity":"MODERATE"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N"}]}