{"id":"CVE-2026-58253","title":"NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system","summary":"NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, when no_auth_user was configured, a parser fast path intended for ordinary client connections could a…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L","cwe":["CWE-287"],"vendor":"linuxfoundation","product":"nats-server","affected":["nats-server < 2.11.16","nats-server >= 2.12.0, < 2.12.7"],"patched":["nats-server 2.12.7"],"published":"2026-07-08","updated":"2026-07-13","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-58253","references":[{"url":"https://github.com/nats-io/nats-server/commit/7b81dd455ea95960090a84858c7662827948d1b6","label":"security-advisories@github.com"},{"url":"https://github.com/nats-io/nats-server/commit/8b8e1ad4ceed32321e00d4fc6e76be05bc13bca6","label":"security-advisories@github.com"},{"url":"https://github.com/nats-io/nats-server/commit/b86147e81710a52b72a7f7275f91d69f723f5cb3","label":"security-advisories@github.com"},{"url":"https://github.com/nats-io/nats-server/releases/tag/v2.11.16","label":"security-advisories@github.com"},{"url":"https://github.com/nats-io/nats-server/releases/tag/v2.12.7","label":"security-advisories@github.com"},{"url":"https://github.com/nats-io/nats-server/releases/tag/v2.14.0","label":"security-advisories@github.com"},{"url":"https://github.com/nats-io/nats-server/security/advisories/GHSA-38x3-76xf-cq45","label":"security-advisories@github.com"}],"tags":["nvd"],"epss":0.00368,"epssPercentile":0.30571,"ingestedAt":"2026-07-13T15:27:34.317Z","slug":"CVE-2026-58253","body":"## Overview\n\nNATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, when no_auth_user was configured, a parser fast path intended for ordinary client connections could also apply to route or leafnode listeners, allowing an unauthenticated peer to bypass inter-server CONNECT authentication and operate with the privileges associated with that connection type. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.\n\n## Affected\n\n- `nats-server < 2.11.16`\n- `nats-server >= 2.12.0, < 2.12.7`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `nats-server 2.12.7`","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}