CVE-2026-33218
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.62%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.62% probability · 48th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-20, CWE-1286
- Affected
- linuxfoundation/nats-server
- Source
- security-advisories@github.com
References
- https://advisories.nats.io/CVE/secnote-2026-10.txtMitigation, Vendor Advisory
- https://github.com/nats-io/nats-server/security/advisories/GHSA-vprv-35vv-q339Mitigation, Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:21769
- https://access.redhat.com/errata/RHSA-2026:22347
- https://access.redhat.com/errata/RHSA-2026:23345
- 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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.