Description
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.
Problem types
CWE-476: NULL Pointer Dereference
Product status
>= 2.12.0-RC.1, < 2.12.5
References
github.com/...server/security/advisories/GHSA-52jh-2xxh-pwh6
github.com/...ommit/a1488de6f2ba6e666aef0f9cce0016f7f167d6a8
advisories.nats.io/CVE/secnote-2026-04.txt