What’s Vulnerable › Vulnerabilities

CVE-2026-58254: NATS Server: Incomplete fix for CVE-2026-33249: Leaf node connections bypass Nats-Trace-Dest permission check

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-08 · updated 2026-10-25
• Weakness: CWE-863

Description

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.8, message trace destination checks were applied to ordinary client connections but not consistently to messages arriving through leafnode connections, allowing a leafnode operator to send trace events to subjects that would not otherwise be permitted and to use trace-only behavior to prevent normal delivery or storage of affected messages. This issue is fixed in versions 2.14.3 and 2.12.8.

Affected products

• nats-io nats-server: before 2.12.8; from 2.14.0 before 2.14.3 — fixed in 2.12.8, 2.14.3

How to fix

Upgrade to a fixed version: nats-io nats-server 2.12.8, 2.14.3. Check the vendor advisory for mitigations.

References

• https://github.com/nats-io/nats-server/commit/cbe845932980b71563efac5cfa4cc751c88936cd
• https://github.com/nats-io/nats-server/releases/tag/v2.12.8
• https://github.com/nats-io/nats-server/releases/tag/v2.14.3
• https://github.com/nats-io/nats-server/security/advisories/GHSA-p3j5-5hrq-p75h

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