CVE-2026-29785

Name	CVE-2026-29785
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
nats-server (PTS)	bookworm	2.9.10-1	vulnerable
	trixie	2.10.27-1	vulnerable
	forky	2.12.4-1	vulnerable
	sid	2.12.6-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
nats-server	source	(unstable)	(unfixed)

Notes

https://github.com/nats-io/nats-server/security/advisories/GHSA-52jh-2xxh-pwh6
Fixed by: https://github.com/nats-io/nats-server/commit/a1488de6f2ba6e666aef0f9cce0016f7f167d6a8 (v2.12.5)
https://advisories.nats.io/CVE/secnote-2026-04.txt