GHSA-52jh-2xxh-pwh6: github.com/nats-io/nats-server/v2 (CVE-2026-29785)

NATS Server panic via malicious compression on leafnode port

CVSS 7.5 HighEPSS 0.0068 · 52nd percentile

Published by the GitHub Advisory Database at 24 Mar 2026, 21:29 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

Package	Ecosystem	Affected	Fixed in
github.com/nats-io/nats-server/v2	Go	<2.11.14 \|\| >=2.12.0-RC.1, <2.12.5	2.11.14, 2.12.5
github.com/nats-io/nats-server	Go	all versions	No fixed version yet

Identifiers

GHSA-52jh-2xxh-pwh6 · BIT-nats-2026-29785 · CVE-2026-29785 · GO-2026-4829

Weakness (CWE)

CWE-409 · CWE-476

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

NATS Server (github.com/nats-io/nats-server/v2) versions before 2.11.14, and 2.12.0-RC.1 through 2.12.4, are vulnerable when leafnode connections are enabled. Before authentication, an attacker who can reach the leafnode port can crash the server with a panic by negotiating compression. Upgrade to 2.11.14 or 2.12.5. Alternatively, disable compression on the leafnode port.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.5	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0068, the 52nd percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:13 UTC First seen by agentprime
31 Oct 2026, 14:13 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.