CVE-2026-29785 | 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.

Published: 2026-03-25 Last update: 2026-03-26 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-29785 is rated Low Risk (37.7/100): CVSS High severity, with low exploitation likelihood (EPSS 0.07%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-29785

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-26 — 0.07% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-29785

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]

Weakness enumeration for CVE-2026-29785

GitHub Security Advisory for CVE-2026-29785

GHSA-52jh-2xxh-pwh6 · Severity: high · Ecosystem: go — NATS Server panic via malicious compression on leafnode port

OS Trackers for CVE-2026-29785

vendor priority summary link
alpine — CVE-2026-29785: 1 source package rows (nats-server); 37 state rows across 2 repos (3.23-community, edge-community); fixed 0, open 37. https://security.alpinelinux.org/vuln/CVE-2026-29785
debian not yet assigned CVE-2026-29785 not yet assigned priority: Debian including 1 source packages (nats-server), 4 status rows across 4 suites (bookworm, forky, sid, trixie): open 2, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-29785
redhat high — https://access.redhat.com/security/cve/CVE-2026-29785
suse high — https://www.suse.com/security/cve/CVE-2026-29785/
ubuntu medium CVE-2026-29785 medium priority: Ubuntu including 1 source packages (nats-server), 4 status rows across 4 suites (jammy, noble, questing, upstream): needs-triage 3, DNE 1. https://ubuntu.com/security/CVE-2026-29785

Affected software / configurations for CVE-2026-29785

Vendor Product Version Raw CPE
linuxfoundation nats-server < 2.11.14 cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*
linuxfoundation nats-server >= 2.12.0, < 2.12.5 cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*

References for CVE-2026-29785

cvelogic Threat Intelligence