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CVE-2026-33247 nats-io CVE debrief

CVE-2026-33247 is a high-severity vulnerability in NATS-Server, a cloud and edge native messaging system. The vulnerability exposes static credentials for all clients provided via argv (the command-line) to any user who can see the monitoring port. The `/debug/vars` end-point contains an unredacted copy of argv. This issue affects NATS-Server versions prior to 2.11.15 and 2.12.6. To mitigate, configure credentials inside a configuration file instead of via argv, and avoid enabling the monitoring port if using secrets in argv. Best practice is to not expose the monitoring port to the Internet or untrusted network sources.

Vendor
nats-io
Product
nats-server
CVSS
HIGH 7.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-03-25
Original CVE updated
2026-06-30
Advisory published
2026-03-25
Advisory updated
2026-06-30

Who should care

Users of NATS-Server, especially those who use static credentials for clients via argv and have the monitoring port enabled, should be aware of this vulnerability. Security teams and administrators responsible for NATS-Server installations should assess their configurations and apply the necessary patches or workarounds.

Technical summary

The vulnerability in NATS-Server arises from the exposure of static client credentials through the `/debug/vars` endpoint when credentials are provided via argv and the monitoring port is enabled. This allows unauthorized access to sensitive information. The issue is addressed in NATS-Server versions 2.11.15 and 2.12.6. The Common Vulnerability Scoring System (CVSS) score for this vulnerability is 7.4, indicating a high severity level.

Defensive priority

High. Immediate action is recommended to patch or mitigate the vulnerability, especially if NATS-Server is used with static credentials via argv and the monitoring port is enabled.

Recommended defensive actions

  • Update NATS-Server to version 2.11.15 or 2.12.6, or later.
  • Configure credentials inside a configuration file instead of via argv.
  • Avoid enabling the monitoring port if using secrets in argv.
  • Limit access to the monitoring port to trusted network sources.
  • Regularly review and update NATS-Server configurations to ensure security best practices are followed.

Evidence notes

The CVE-2026-33247 vulnerability is documented in the official CVE record and the National Vulnerability Database (NVD). The issue is confirmed by the NATS.io security advisory and addressed in versions 2.11.15 and 2.12.6 of NATS-Server. Additional information and mitigation strategies are provided by Red Hat security advisories.

Official resources

This article is AI-assisted and based on the supplied source corpus.