What is CVE-2026-33218?

CVE-2026-33218 is a high-severity vulnerability in Nats-io Nats-server, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2026-03-25.

How severe is CVE-2026-33218?

High severity. CVSS v3 base score is 7.5 out of 10.

Improper input validation in Nats-io Nats-server

CVE-2026-33218

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 client which can connect to the leafnode port can crash the nats-server with a certain malformed messag…

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

EPSS: 0.001 (20.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: 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 — versions < < 2.11.15, >= 2.12.0-RC.1, < 2.12.6

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339 (x_refsource_CONFIRM)
https://advisories.nats.io/CVE/secnote-2026-10.txt (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-33218?: CVE-2026-33218 is a high-severity vulnerability in Nats-io Nats-server, classified under Improper Input Validation. CVSS score: 7.5/10. Published 2026-03-25.
How severe is CVE-2026-33218?: High severity. CVSS v3 base score is 7.5 out of 10.