Description
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Starting in version 2.2.0 and prior to versions 2.11.14 and 2.12.5, a missing sanity check on a WebSockets frame could trigger a server panic in the nats-server. This happens before authentication, and so is exposed to anyone who can connect to the websockets port. Versions 2.11.14 and 2.12.5 contains a fix. A workaround is available. The vulnerability only affects deployments which use WebSockets and which expose the network port to untrusted end-points. If one is able to do so, a defense in depth of restricting either of these will mitigate the attack.
Affected products
linuxfoundation: nats-server
References8
- advisories.nats.io/CVE/secnote-2026-03.txt MitigationVendor Advisory
- github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rc… MitigationVendor Advisory
- access.redhat.com/errata/RHSA-2026:21769
- access.redhat.com/errata/RHSA-2026:22347
- access.redhat.com/errata/RHSA-2026:23345
- access.redhat.com/security/cve/CVE-2026-27889
- bugzilla.redhat.com/show_bug.cgi?id=2451447
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27889…
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 49 · as of 12 November 2026
- CWE
- CWE-190CWE-1286
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