{"answers":{"affected":"9 open source packages ship an affected version, including github.com/nats-io/nats-server/v2, nats and github.com/nats-io/nats-server. It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-33248 in the wild and no public exploit code.","fix":"Upgrade github.com/nats-io/nats-server/v2 to a fixed version for your release line: 2.11.15 or 2.12.6.","what":"CVE-2026-33248 is a medium-severity authentication bypass vulnerability in nats-io nats-server, published on 25 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-33248 and fix it if it is affected.\n\nWhat it is: CVE-2026-33248 is a medium-severity authentication bypass vulnerability in nats-io nats-server, published on 25 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2026-33248 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- github.com/nats-io/nats-server/v2 (Go): affected all versions; fixed in 2.11.15, 2.12.6\n- github.com/nats-io/nats-server/v2 (Go): affected all versions; fixed in 2.11.15\n- github.com/nats-io/nats-server/v2 (Go): affected all versions; fixed in 2.11.15\n- github.com/nats-io/nats-server/v2 (Go): affected from 2.12.0-RC.1; fixed in 2.12.6\n- github.com/nats-io/nats-server/v2 (Go): affected from 2.12.0-RC.1; fixed in 2.12.6\n- nats (Bitnami): affected all versions; fixed in 2.11.15, 2.12.6\n- github.com/nats-io/nats-server (Go): affected all versions; no fix listed\n- github.com/nats-io/nats-server (Go): affected all versions; no fix listed\n- github.com/nats-io/nats-server (Go): affected all versions; no fix listed\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-33248/ (Markdown: https://insights.sbomify.com/CVE-2026-33248/index.md)","id":"CVE-2026-33248","markdown":"https://insights.sbomify.com/CVE-2026-33248/index.md","name":"CVE-2026-33248","record":{"aliases":["BIT-nats-2026-33248","CLEANSTART-2026-YK24413","DEBIAN-CVE-2026-33248","ECHO-eee5-ed4c-8425","GHSA-3f24-pcvm-5jqc","GO-2026-4828","JLSEC-2026-1132","MINI-f3qw-574r-82r8","MINI-hpmr-qhpr-vwx5","MINI-m4rq-hjc2-x6cv","MINI-v6rp-h4rm-6h26","MINI-vm65-vpxh-8p3q","MINI-x2fx-7f63-qxqh","MINI-xjf2-fgj2-3jrp","ROOT-APP-GOBINARY-CVE-2026-33248","UBUNTU-CVE-2026-33248"],"analysis":{"component_type":"server_software","fix_type":"upgrade","impacts":["security_bypass"],"network_reachable":"yes","non_default_config":true,"product_category":"NATS messaging server","requires_auth":"low_privilege","summary":"Attackers with valid certificates can bypass mTLS authentication in NATS Server if specific Subject DN patterns are used, requiring an upgrade to fix.","user_interaction":"not_required","vuln_class":"auth_bypass"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"nats-server","vendor":"linuxfoundation"}],"cvss":{"score":4.2,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-295","name":"Improper Certificate Validation"},{"id":"CWE-287","name":"Improper Authentication"}],"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.","ecosystems":["Bitnami","Go"],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"NATS has mTLS verify_and_map authentication bypass via incorrect Subject DN matching","id":"CVE-2026-33248","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Bitnami","product":null,"products":[],"type":"auth_bypass","year":"2026"},"n_packages":9,"n_references":2,"next":{"headline":"NATS: Message tracing can be redirected to arbitrary subject","id":"CVE-2026-33249"},"packages":[{"ecosystem":"Bitnami","fixed":["2.11.15","2.12.6"],"introduced":["0","2.12.0"],"last_affected":[],"package":"nats","purl":"pkg:bitnami/nats","source":"BIT-nats-2026-33248"},{"ecosystem":"Go","fixed":[],"introduced":["0"],"last_affected":[],"package":"github.com/nats-io/nats-server","purl":null,"source":"GHSA-3f24-pcvm-5jqc"},{"ecosystem":"Go","fixed":[],"introduced":["0"],"last_affected":[],"package":"github.com/nats-io/nats-server","purl":"pkg:golang/github.com/nats-io/nats-server","source":"GHSA-3f24-pcvm-5jqc"},{"ecosystem":"Go","fixed":[],"introduced":["0"],"last_affected":[],"package":"github.com/nats-io/nats-server","purl":"pkg:golang/github.com/nats-io/nats-server","source":"GO-2026-4828"},{"ecosystem":"Go","fixed":["2.11.15","2.12.6"],"introduced":["0","2.12.0-RC.1"],"last_affected":[],"package":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","source":"GO-2026-4828"},{"ecosystem":"Go","fixed":["2.11.15"],"introduced":["0"],"last_affected":[],"package":"github.com/nats-io/nats-server/v2","purl":null,"source":"GHSA-3f24-pcvm-5jqc"},{"ecosystem":"Go","fixed":["2.11.15"],"introduced":["0"],"last_affected":[],"package":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","source":"GHSA-3f24-pcvm-5jqc"},{"ecosystem":"Go","fixed":["2.12.6"],"introduced":["2.12.0-RC.1"],"last_affected":[],"package":"github.com/nats-io/nats-server/v2","purl":null,"source":"GHSA-3f24-pcvm-5jqc"},{"ecosystem":"Go","fixed":["2.12.6"],"introduced":["2.12.0-RC.1"],"last_affected":[],"package":"github.com/nats-io/nats-server/v2","purl":"pkg:golang/github.com/nats-io/nats-server/v2","source":"GHSA-3f24-pcvm-5jqc"}],"prev":{"headline":"NATS credentials are exposed in monitoring port via command-line argv","id":"CVE-2026-33247"},"products":["nats-server"],"published":"2026-03-25","related":[{"cvss_score":9.8,"headline":"NATS nats-server allows directory traversal via unintended path to a management action","id":"CVE-2022-28357","kev_date_added":null,"published":"2023-09-19"},{"cvss_score":8.8,"headline":"NATS Server: Route API Auth Bypass","id":"CVE-2026-58253","kev_date_added":null,"published":"2026-07-08"},{"cvss_score":8.8,"headline":"Incorrect Authorization in NATS nats-server","id":"CVE-2022-24450","kev_date_added":null,"published":"2022-02-08"},{"cvss_score":8.6,"headline":"NATS has MQTT plaintext password disclosure","id":"CVE-2026-33216","kev_date_added":null,"published":"2026-03-25"},{"cvss_score":7.7,"headline":"NATS Server: Remote crash via integer overflow in Connz pagination","id":"CVE-2026-58207","kev_date_added":null,"published":"2026-07-08"},{"cvss_score":7.5,"headline":"NATS Server: MQTT partial CONNECT packets can exhaust pre-auth memory","id":"CVE-2026-58210","kev_date_added":null,"published":"2026-07-08"},{"cvss_score":7.5,"headline":"NATS Server: Pre-auth server crash via double INFO in leafnode handshake","id":"CVE-2026-58250","kev_date_added":null,"published":"2026-07-08"}],"sources":[{"class":"attribution","licence":"Apache-2.0","name":"Bitnami","prefix":"BIT"},{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"Go Vulnerability Database","prefix":"GO"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-03-26","vendors":["nats-io"]},"summary":"Attackers with valid certificates can bypass mTLS authentication in NATS Server if specific Subject DN patterns are used, requiring an upgrade to fix.","url":"https://insights.sbomify.com/CVE-2026-33248/"}