CVE-2026-33218
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
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 Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| nats-io | nats-server | < < 2.11.15 | affected |
| nats-io | nats-server | >= 2.12.0-RC.1, < 2.12.6 | affected |
Weaknesses
- CWE-20: CWE-20: Improper Input Validation
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: none
- Automatable: yes
- Technical Impact: partial
nats-server: github.com/nats-io/nats-server: NATS-Server: Denial of Service via malformed message pre-authentication on leafnode port
Additional References
- https://access.redhat.com/security/cve/CVE-2026-33218
- https://bugzilla.redhat.com/show_bug.cgi?id=2451450
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33218.json
- https://access.redhat.com/errata/RHSA-2026:22347
- https://access.redhat.com/errata/RHSA-2026:21769
- https://access.redhat.com/errata/RHSA-2026:23345
References
- https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339
- https://advisories.nats.io/CVE/secnote-2026-10.txt
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