CVE-2026-29785

HIGH 7.5

NATS Server panic via malicious compression on leafnode port

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-476
Vendor	nats-io
Product	nats-server
Published	Mar 25, 2026
Last Updated	Jul 20, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

nats-io / nats-server

< 2.11.14 >= 2.12.0-RC.1, < 2.12.5

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/nats-io/nats-server/security/advisories/GHSA-52jh-2xxh-pwh6 github.com: https://github.com/nats-io/nats-server/commit/a1488de6f2ba6e666aef0f9cce0016f7f167d6a8 advisories.nats.io: https://advisories.nats.io/CVE/secnote-2026-04.txt access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-29785 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2451444 security.access.redhat.com: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-29785.json access.redhat.com: https://access.redhat.com/errata/RHSA-2026:22347 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:23345 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:21769