Bug 2498266 (CVE-2026-58254)

Summary: CVE-2026-58254 nats-server: NATS Server: Denial of Service via inconsistent message trace destination checks
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in NATS Server. Message trace destination checks, which ensure that trace events are sent to authorized subjects, were not consistently applied to messages originating from leafnode connections. This inconsistency allows a leafnode operator to bypass these checks and send trace events to subjects that should otherwise be restricted. The primary consequence of this vulnerability is that it can be used to prevent the normal delivery or storage of affected messages, leading to a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-07-08 21:03:00 UTC 
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.8, message trace destination checks were applied to ordinary client connections but not consistently to messages arriving through leafnode connections, allowing a leafnode operator to send trace events to subjects that would not otherwise be permitted and to use trace-only behavior to prevent normal delivery or storage of affected messages. This issue is fixed in versions 2.14.3 and 2.12.8.