NATS Server panic via malicious compression on leafnode port
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.
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-29785US | — | — | ||
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" configur… | ||||
references
External citations — patches, advisories, analysis.
- https://access.redhat.com/errata/RHSA-2026:21769WEB
- https://access.redhat.com/errata/RHSA-2026:22347WEB
- https://access.redhat.com/errata/RHSA-2026:23345WEB
- https://access.redhat.com/security/cve/CVE-2026-29785WEB
- https://advisories.nats.io/CVE/secnote-2026-04.txtADVISORY
- https://bugzilla.redhat.com/show_bug.cgi?id=2451444WEB
- https://github.com/nats-io/nats-server/commit/a1488de6f2ba6e666aef0f9cce0016f7f167d6a8FIX
- https://github.com/nats-io/nats-server/security/advisories/GHSA-52jh-2xxh-pwh6ADVISORY
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