CVE-2026-33218
HIGHDescription
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 message pre-authentication. Versions 2.11.15 and 2.12.6 contain a fix. As a workaround, disable leafnode support if not needed or restrict network connections to the leafnode port, if plausible without compromising the service offered.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploit Intelligence
Moderate risk: more likely to be exploited than 57% of all known CVEs.
References
Related Vulnerabilities
Other CWE-20 (Improper Input Validation) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-3400 | Critical | 10.0 | 100% | KEV + Ransom | - |
| CVE-2021-45105 | Medium | 5.9 | 100% | - | Fix |
| CVE-2021-44228 | Critical | 10.0 | 100% | KEV + Ransom | Fix |
| CVE-2021-21985 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2020-3452 | High | 7.5 | 100% | KEV | Fix |
| CVE-2018-7600 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
Common questions
How do I fix CVE-2026-33218?
Upgrade nats-server on debian unstable to 2.12.6-1 or later.
Is CVE-2026-33218 being actively exploited?
Not that we know of. CVE-2026-33218 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.84% is the estimated probability that it will be exploited in the next 30 days. That is higher than 57% of all scored CVEs.
How severe is CVE-2026-33218?
CVE-2026-33218 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-33218 affect?
Published advisories record a fix for nats-server (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-33218
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-09.