High severityNVD Advisory· Published Mar 25, 2026· Updated Mar 26, 2026
NATS has pre-auth server panic via leafnode handling
CVE-2026-33218
Description
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.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
github.com/nats-io/nats-server/v2Go | < 2.11.15 | 2.11.15 |
github.com/nats-io/nats-server/v2Go | >= 2.12.0-RC.1, < 2.12.6 | 2.12.6 |
github.com/nats-io/nats-serverGo | >= 0 | — |
Affected products
1- Range: < < 2.11.15
Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
4- github.com/advisories/GHSA-vprv-35vv-q339ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-33218ghsaADVISORY
- advisories.nats.io/CVE/secnote-2026-10.txtghsax_refsource_MISCWEB
- github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339ghsax_refsource_CONFIRMWEB
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