{"id":"UBUNTU-CVE-2026-33248","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.","modified":"2026-07-02T18:02:55.282307053Z","published":"2026-03-25T21:16:00Z","upstream":["CVE-2026-33248"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-33248"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-33248"},{"type":"REPORT","url":"https://advisories.nats.io/CVE/secnote-2026-13.txt"},{"type":"REPORT","url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-3f24-pcvm-5jqc"}],"affected":[{"package":{"name":"nats-server","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/nats-server?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.9.19-1build1","2.10.3-1","2.10.4-1","2.10.7-1","2.10.7-1ubuntu0.1","2.10.7-1ubuntu0.2","2.10.7-1ubuntu0.3"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-github-nats-io-nats-server-dev","binary_version":"2.10.7-1ubuntu0.3"},{"binary_name":"nats-server","binary_version":"2.10.7-1ubuntu0.3"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33248.json"}},{"package":{"name":"nats-server","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/nats-server?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.10.24-1","2.10.27-1"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-github-nats-io-nats-server-dev","binary_version":"2.10.27-1"},{"binary_version":"2.10.27-1","binary_name":"nats-server"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33248.json"}},{"package":{"name":"nats-server","ecosystem":"Ubuntu:Pro:26.04:LTS","purl":"pkg:deb/ubuntu/nats-server?arch=source&distro=esm-apps%2Fresolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.10.27-1","2.10.27-1build1","2.10.27-1ubuntu0.26.04.1~esm1"],"ecosystem_specific":{"binaries":[{"binary_name":"golang-github-nats-io-nats-server-dev","binary_version":"2.10.27-1ubuntu0.26.04.1~esm1"},{"binary_name":"nats-server","binary_version":"2.10.27-1ubuntu0.26.04.1~esm1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33248.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}