Junglewise Threat Intelligence

CVE-2026-29785: nats-io nats-server NULL pointer dereference in leafnode protocol

CVE-2026-29785 · Severity: high · CVSS 7.5 · Published 2026-03-25

Technologies: Nats-Io NATS Server, Red Hat Multicluster Global Hub. Vendors: Go, Red Hat.

Executive brief

NATS-Server, a high-performance messaging system used for cloud and edge computing, is vulnerable to a denial-of-service attack. If the 'leafnode' feature is enabled, an unauthenticated remote attacker can crash the server by sending specific commands before the connection is fully established. This results in a complete service outage, potentially disrupting data communication between distributed systems or IoT devices.

Technical details

A NULL pointer dereference (CWE-476) exists in NATS-Server's leafnode protocol handling. When compression is enabled on a leafnode port (typically 7422), the server may process 'LS+' (Leafnode Subscribe) commands before the 'CONNECT' command has been fully processed, leading to a nil pointer access for the client account object. This vulnerability is reachable over the network without authentication. The issue is fixed in versions 2.11.14 and 2.12.5. A known workaround is to disable compression within the leafnodes configuration block.

Affected products

  • nats-io nats-server < 2.11.14, >= 2.12.0-RC.1 < 2.12.5
  • Red Hat Multicluster Global Hub 1.4.5, 1.5.4, 1.6.2

Timeline

  • 2026-03-02: other: Fix authored by maintainers
  • 2026-03-09: advisory: Internal advisory date
  • 2026-03-25: disclosed: Public disclosure of CVE-2026-29785
  • 2026-03-25: patched: Fixed versions released

References

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