Auth bypass in Nats-io Nats-server
CVE-2026-58253
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 als…
Vulnerability class: Broken Authentication
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:H/A:L.
Affected products
- Nats-io Nats-server — versions < 2.11.16, >= 2.12.0-preview.1, < 2.12.6
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC)
- security-advisories@github.com (x_refsource_CONFIRM)
Frequently asked questions
- What is CVE-2026-58253?
- CVE-2026-58253 is a high-severity vulnerability in Nats-io Nats-server, classified under Improper Authentication. CVSS score: 8.8/10. Published 2026-07-08.
- How severe is CVE-2026-58253?
- High severity. CVSS v3 base score is 8.8 out of 10.