What is CVE-2026-33219?

CVE-2026-33219 is a medium-severity vulnerability in Nats-io Nats-server, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.3/10. Published 2026-03-25.

How severe is CVE-2026-33219?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Resource exhaustion in Nats-io Nats-server

CVE-2026-33219

NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.15 and 2.12.6, a malicious client which can connect to the WebSockets port can cause unbounded memory use in the nats-se…

EPSS: 0.001 (30.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

Affected products

Nats-io Nats-server — versions < 2.11.15, >= 2.12.0-RC.1, < 2.12.6

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

https://github.com/nats-io/nats-server/security/advisories/GHSA-8r68-gvr4-jh7j (x_refsource_CONFIRM)
https://advisories.nats.io/CVE/secnote-2026-02.txt (x_refsource_MISC)
https://advisories.nats.io/CVE/secnote-2026-11.txt (x_refsource_MISC)
https://github.com/advisories/GHSA-qrvq-68c2-7grw (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-33219?: CVE-2026-33219 is a medium-severity vulnerability in Nats-io Nats-server, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.3/10. Published 2026-03-25.
How severe is CVE-2026-33219?: Medium severity. CVSS v3 base score is 5.3 out of 10.