PT-2026-27621 · Nats.Io · Nats Server

Published 2026-03-24 · Updated 2026-05-21 · CVE-2026-33248

Positive Technologies (AI Summary)

CVSS v3.1

4.2

Medium

Base vector

AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

Name of the Vulnerable Software and Affected Versions NATS-Server versions prior to 2.11.15 NATS-Server versions prior to 2.12.6

Description NATS-Server, a high-performance server for NATS.io, a cloud and edge native messaging system, has an issue where, 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 Relative Distinguished Name (RDN) are not correctly enforced, potentially allowing for authentication bypass. This requires a valid certificate from a trusted Certificate Authority (CA) and specific DN naming patterns. The maintainers consider exploitation unlikely, but sophisticated administrators with specific DN construction patterns might be impacted.

Recommendations Update NATS-Server to version 2.11.15 or later. Update NATS-Server to version 2.12.6 or later. Review CA issuing practices.

Exploit

Fix

Improper Authentication

Improper Certificate Validation

Weakness Enumeration

CWE-287

CWE-295

Related Identifiers

BIT-NATS-2026-33248

CVE-2026-33248

GHSA-3F24-PCVM-5JQC

GO-2026-4828

SUSE-SU-2026:1135-1

Affected Products

Nats Server

References · 157

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33248.json · Exploit
• https://github.com/nats-io/nats-server/security/advisories/GHSA-3f24-pcvm-5jqc · Vendor Advisory
• https://advisories.nats.io/CVE/secnote-2026-13.txt · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-33248 · Security Note
• https://osv.dev/vulnerability/UBUNTU-CVE-2026-33248 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:1135-1 · Vendor Advisory
• https://osv.dev/vulnerability/ROOT-APP-GOBINARY-CVE-2026-33248 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-33248 · Vendor Advisory
• https://cve.org/CVERecord?id=CVE-2026-33248 · Security Note
• https://ubuntu.com/security/CVE-2026-33248 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-3f24-pcvm-5jqc · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-33248 · Vendor Advisory
• https://osv.dev/vulnerability/DEBIAN-CVE-2026-33248 · Vendor Advisory
• https://osv.dev/vulnerability/BIT-nats-2026-33248 · Vendor Advisory
• https://osv.dev/vulnerability/GO-2026-4828 · Vendor Advisory