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Vulnerability · Published Jul 8, 2026 · Assigned by GitHub_M

CVE-2026-58250NATS Server: Pre-auth server crash via double INFO in leafnode handshake

High 7.5

In plain English

A high-severity null pointer dereference in nats-server from nats-io. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 55% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.7%top 45.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.12.8 and 2.11.17, an unauthenticated peer with network access to a leafnode listener with compression enabled could crash the server during the pre-authentication leafnode handshake by sending repeated leafnode INFO protocol messages before authentication and account setup completed. This issue is fixed in versions 2.12.8 and 2.11.17.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12nats-serverno fix listedDEBIAN-CVE-2026-58250
Debian:13nats-serverno fix listedDEBIAN-CVE-2026-58250
Debian:14nats-server2.14.1-1DEBIAN-CVE-2026-58250
Ubuntu:24.04:LTSnats-serverno fix listedUBUNTU-CVE-2026-58250
Ubuntu:25.10nats-serverno fix listedUBUNTU-CVE-2026-58250

Affected products (as reported)

VendorProductVersions
nats-io nats-server < 2.11.17>= 2.12.0-preview.1, < 2.12.8

Weakness: CWE-476 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References