What’s Vulnerable › Vulnerabilities

CVE-2026-58213: NATS Server: MQTT SUBSCRIBE Protocol Injection via Leaf Node/Route Forwarding allows arbitrary NATS command injection

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% 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-74

Description

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.1 and 2.12.9, an MQTT client could include protocol control characters in subscription filters that were later forwarded as NATS protocol data to route or leafnode connections, corrupting the forwarded protocol stream and allowing injection of unintended NATS protocol operations. This issue is fixed in versions 2.14.1 and 2.12.9.

Affected products

• nats-io nats-server: before 2.12.9; from 2.14.0 before 2.14.1 — fixed in 2.12.9, 2.14.1

How to fix

Upgrade to a fixed version: nats-io nats-server 2.12.9, 2.14.1. Check the vendor advisory for mitigations.

References

• https://github.com/nats-io/nats-server/commit/366837cfc65ab9ccb4f98193c65e8daf238582d8
• https://github.com/nats-io/nats-server/commit/64ebae40051ee497c481e10f316238faf0de1736
• https://github.com/nats-io/nats-server/commit/f14856b9e57a36818f43851cb69b6e33670885c9
• https://github.com/nats-io/nats-server/pull/8163
• https://github.com/nats-io/nats-server/pull/8164
• https://github.com/nats-io/nats-server/releases/tag/v2.12.9
• https://github.com/nats-io/nats-server/releases/tag/v2.14.1
• https://github.com/nats-io/nats-server/security/advisories/GHSA-qrcv-3558-gj4f

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