nats-io nats-server up to 2.11.15/2.12.6 Subscription Deny Evaluation improper authentication

Summaryinfo

A vulnerability identified as problematic has been detected in nats-io nats-server up to 2.11.15/2.12.6. This vulnerability affects unknown code of the component Subscription Deny Evaluation. The manipulation leads to improper authentication. This vulnerability is listed as CVE-2026-58251. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in nats-io nats-server up to 2.11.15/2.12.6. It has been rated as problematic. This issue affects some unknown functionality of the component Subscription Deny Evaluation. The manipulation with an unknown input leads to a improper authentication vulnerability. Using CWE to declare the problem leads to CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. Impacted is confidentiality. The summary by CVE is:

NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.0, 2.12.7, and 2.11.16, an authenticated user with subscription deny permissions could bypass a plain subject deny rule by using a queue subscription, because queue-specific deny evaluation could override the plain subject deny result when the queue name itself was not denied. This issue is fixed in versions 2.14.0, 2.12.7, and 2.11.16.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-58251 since 06/29/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available.

Upgrading to version 2.11.16, 2.12.7 or 2.14.0 eliminates this vulnerability.

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Productinfo

Vendor

• nats-io

Name

• nats-server

Version

• 2.11.0
• 2.11.1
• 2.11.2
• 2.11.3
• 2.11.4
• 2.11.5
• 2.11.6
• 2.11.7
• 2.11.8
• 2.11.9
• 2.11.10
• 2.11.11
• 2.11.12
• 2.11.13
• 2.11.14
• 2.11.15
• 2.12.0
• 2.12.1
• 2.12.2
• 2.12.3
• 2.12.4
• 2.12.5
• 2.12.6

Website

• Product: https://github.com/nats-io/nats-server/

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