CVE-2026-58210

NATS Server: MQTT partial CONNECT packets can exhaust pre-auth memory

CVSS 7.5 HIGHCWE-400

Vexday Risk Score

18Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 7.5EPSS —KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

08 Jul 2026Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, an unauthenticated MQTT client could cause the server to retain large incomplete MQTT CONNECT packets before authentication completed, consuming server memory while the parser waited for the advertised MQTT packet length. This issue is fixed in versions 2.14.3 and 2.12.12.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

nats-io · nats-server

References

https://github.com/nats-io/nats-server/commit/bce9ef39469e610aeddb819194ceb7f7edfc0861 https://github.com/nats-io/nats-server/commit/e016e47bbf70304945f2ae9dc397e4862adefaf5 https://github.com/nats-io/nats-server/releases/tag/v2.12.12 https://github.com/nats-io/nats-server/releases/tag/v2.14.3 https://github.com/nats-io/nats-server/security/advisories/GHSA-r72h-j7qq-v6qg