{"cve":"CVE-2026-33248","nvd":{"published":"2026-03-25T21:16:47.563","modified":"2026-06-17T10:37:11.377","status":"Analyzed","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N","score":4.2},"cwes":["CWE-287","CWE-295"],"references":["https://advisories.nats.io/CVE/secnote-2026-13.txt","https://github.com/nats-io/nats-server/security/advisories/GHSA-3f24-pcvm-5jqc"],"products":["linuxfoundation:nats-server"],"source":"nvd","synced_at":"2026-10-19T22:28:18.033120106+00:00"},"epss":{"cve":"CVE-2026-33248","score":0.00149,"percentile":0.04068,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-3f24-pcvm-5jqc","url":"https://osv.dev/vulnerability/GHSA-3f24-pcvm-5jqc","summary":"NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching","modified":"2026-09-10T03:50:36.808606306Z","packages":[{"ecosystem":"Go","name":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","ranges":["<2.11.15"],"fixed":["2.11.15"]},{"ecosystem":"Go","name":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","ranges":[">=2.12.0-RC.1 <2.12.6"],"fixed":["2.12.6"]},{"ecosystem":"Go","name":"github.com/nats-io/nats-server","purl":"pkg:golang/github.com/nats-io/nats-server","ranges":["all versions"],"fixed":[]}]},{"id":"GO-2026-4828","url":"https://osv.dev/vulnerability/GO-2026-4828","summary":"NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching in github.com/nats-io/nats-server","modified":"2026-03-27T18:26:05.115118Z","packages":[{"ecosystem":"Go","name":"github.com/nats-io/nats-server","purl":"pkg:golang/github.com/nats-io/nats-server","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","ranges":["<2.11.15",">=2.12.0-RC.1 <2.12.6"],"fixed":["2.11.15","2.12.6"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}