NATS Server: Pre-auth server crash via double INFO in leafnode handshake (CVE-2026-58250)
NATS Server versions prior to 2.12.8 and 2.11.17 contain a vulnerability where an unauthenticated peer with network access to a leafnode listener with compression enabled can crash the server by sending repeated leafnode INFO protocol messages during the pre-authentication handshake. This flaw allows denial of service by crashing the server before authentication and account setup complete. The issue is fixed in versions 2.12.8 and 2.11.17.
AI Analysis
Technical Summary
NATS Server, a messaging system server, has a denial-of-service vulnerability (CVE-2026-58250) in versions before 2.12.8 and 2.11.17. An unauthenticated attacker with network access to a leafnode listener configured with compression can cause the server to crash during the pre-authentication leafnode handshake by sending multiple INFO protocol messages before authentication and account setup are finalized. This vulnerability is addressed by fixes in versions 2.12.8 and 2.11.17.
Potential Impact
An unauthenticated attacker with network access to a leafnode listener can cause a denial of service by crashing the NATS Server during the pre-authentication handshake phase. This disrupts service availability but does not indicate code execution or data compromise based on the provided data.
Mitigation Recommendations
Apply the official fixes by upgrading NATS Server to version 2.12.8 or later, or 2.11.17 or later. These versions contain the patch that prevents the server crash caused by repeated INFO messages during the leafnode handshake. No other mitigation is indicated.
NATS Server: Pre-auth server crash via double INFO in leafnode handshake (CVE-2026-58250)
Description
NATS Server versions prior to 2.12.8 and 2.11.17 contain a vulnerability where an unauthenticated peer with network access to a leafnode listener with compression enabled can crash the server by sending repeated leafnode INFO protocol messages during the pre-authentication handshake. This flaw allows denial of service by crashing the server before authentication and account setup complete. The issue is fixed in versions 2.12.8 and 2.11.17.
Affected software
pkg:deb/ubuntu/[email protected]?arch=source&distro=noblepkg:deb/ubuntu/[email protected]?arch=source&distro=questingpkg:deb/ubuntu/[email protected]~esm1?arch=source&distro=esm-apps/resoluteRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
NATS Server, a messaging system server, has a denial-of-service vulnerability (CVE-2026-58250) in versions before 2.12.8 and 2.11.17. An unauthenticated attacker with network access to a leafnode listener configured with compression can cause the server to crash during the pre-authentication leafnode handshake by sending multiple INFO protocol messages before authentication and account setup are finalized. This vulnerability is addressed by fixes in versions 2.12.8 and 2.11.17.
Potential Impact
An unauthenticated attacker with network access to a leafnode listener can cause a denial of service by crashing the NATS Server during the pre-authentication handshake phase. This disrupts service availability but does not indicate code execution or data compromise based on the provided data.
Mitigation Recommendations
Apply the official fixes by upgrading NATS Server to version 2.12.8 or later, or 2.11.17 or later. These versions contain the patch that prevents the server crash caused by repeated INFO messages during the leafnode handshake. No other mitigation is indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- UBUNTU-CVE-2026-58250
- Osv Schema Version
- 1.7.0
- Ecosystems
- ["Ubuntu:24.04:LTS","Ubuntu:25.10","Ubuntu:Pro:26.04:LTS"]
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6a58b45d68715ace43d6be35
Added to database: 07/16/2026, 10:37:17 UTC
Last enriched: 09/08/2026, 15:19:40 UTC
Last updated: 09/14/2026, 10:01:32 UTC
Views: 29
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