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.

Project Subscriptions

No data.

Advisories
Source ID Title
Github GHSA Github GHSA GHSA-pq2q-rcw4-3hr6 NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Wed, 25 Mar 2026 20:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 25 Mar 2026 19:45:00 +0000

Type Values Removed Values Added
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.
Title NATS: Pre-auth remote server crash via WebSocket frame length overflow in wsRead
Weaknesses CWE-190
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


Projects

Sign in to view the affected projects.

cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-25T20:06:31.897Z

Reserved: 2026-02-24T15:19:29.716Z

Link: CVE-2026-27889

cve-icon Vulnrichment

Updated: 2026-03-25T20:06:28.024Z

cve-icon NVD

Status : Received

Published: 2026-03-25T20:16:27.210

Modified: 2026-03-25T20:16:27.210

Link: CVE-2026-27889

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses