CVE-2026-27889

Severity CVSS v4.0:

Pending analysis

Type:

CWE-190 Integer Overflow or Wraparound

Publication date:

25/03/2026

Last modified:

26/03/2026

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.

Impact

Vector 3.x

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.50 HIGH
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector (AV): Network
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): None
Integrity (I): None
Availability (A): High

Base Score 3.x

7.50

Severity 3.x

HIGH

Vulnerable products and versions

CPE	From	Up to
cpe:2.3:a:linuxfoundation:nats-server::::::::	2.2.0 (including)	2.11.14 (excluding)
cpe:2.3:a:linuxfoundation:nats-server::::::::	2.12.0 (including)	2.12.5 (excluding)

To consult the complete list of CPE names with products and versions, see this page

CVE-2026-27889

Description

Impact

Vulnerable products and versions

References to Advisories, Solutions, and Tools