CVE-2026-27889
NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system.
Impact
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 packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/nats-io/nats-server/v2 | >= 2.2.0, < 2.11.14 | 2.11.14 |
| go | github.com/nats-io/nats-server | > 0 | none recorded |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Linuxfoundation | Nats-Server | from 2.2.0 before 2.11.14 from 2.12.0 before 2.12.5 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-pq2q-rcw4-3hr6
- https://github.com/nats-io/nats-server/security/advisories/GHSA-pq2q-rcw4-3hr6
- https://advisories.nats.io/CVE/secnote-2026-03.txt
- https://nvd.nist.gov/vuln/detail/CVE-2026-27889
- 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-2026-27889
- https://bugzilla.redhat.com/show_bug.cgi?id=2451447
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27889.json