NATS-Server is a High-Performance server for NATS.io, a cloud and edge native messaging system. Prior to versions 2.11.14 and 2.12.5, if the nats-server has the "leafnode" configuration enabled (not default), then anyone who can connect can crash the nats-server by triggering a panic. This happens pre-authentication and requires that compression be enabled (which it is, by default, when leafnodes are used).
Versions 2.11.14 and 2.12.5 contain a fix. As a workaround, disable compression on the leafnode port.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service
CVSS Vector v3.1
Weakness Type (CWE)
Vulnerable Products 2
| Configuration | From (including) | Up to (excluding) |
|---|---|---|
|
Linuxfoundation Nats-Server
cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*
|
— |
2.11.14
|
|
Linuxfoundation Nats-Server
cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*
|
2.12.0
|
2.12.5
|
References 3
https://advisories.nats.io/CVE/secnote-2026-04.txt
security-advisories@github.com
https://github.com/nats-io/nats-server/commit/a1488de6f2ba6e666aef0f9cce0016f7f…
security-advisories@github.com
https://github.com/nats-io/nats-server/security/advisories/GHSA-52jh-2xxh-pwh6
security-advisories@github.com