CVE-2026-58207 in nats-server
Summary
by MITRE • 07/08/2026
NATS Server is a high-performance server for NATS.io, the cloud and edge native messaging system. Prior to 2.14.3 and 2.12.12, a client able to send account-scoped connection monitoring requests could crash the server by supplying Connz pagination Offset and Limit values that overflowed internal arithmetic before the response window was safely bounded. This issue is fixed in versions 2.14.3 and 2.12.12.
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Analysis
by VulDB Data Team • 07/08/2026
The NATS Server represents a critical component in cloud and edge native messaging architectures, serving as the backbone for high-performance message passing systems that support thousands of concurrent connections. This vulnerability affects the server's handling of connection monitoring requests within account-scoped contexts, where legitimate clients can manipulate pagination parameters to trigger unexpected behavior. The flaw specifically resides in how the server processes Connz pagination offset and limit values during connection monitoring operations, creating a scenario where arithmetic overflow conditions can occur before proper response window validation takes place.
The technical implementation of this vulnerability stems from inadequate input validation within the connection monitoring request processing pipeline. When clients submit account-scoped connection monitoring requests with carefully crafted pagination parameters, the server's internal arithmetic operations fail to properly bound the offset and limit values before performing calculations. This overflow condition occurs in the server's response generation logic where it attempts to determine the appropriate window of connection data to return based on user-specified pagination parameters. The vulnerability manifests as a server crash rather than a more subtle denial of service, indicating that the arithmetic overflow results in memory corruption or invalid pointer dereferences within the server's connection management subsystem.
Operationally, this vulnerability creates significant risk for organizations relying on NATS Server for mission-critical messaging infrastructure, particularly those implementing account-scoped monitoring capabilities. An attacker with access to send connection monitoring requests could intentionally cause server crashes, leading to service disruption and potential data loss in distributed systems. The impact extends beyond simple availability concerns as the vulnerability affects the core functionality of connection management within the NATS ecosystem, potentially compromising the integrity of messaging flows and monitoring capabilities that organizations depend upon for operational visibility.
The fix implemented in versions 2.14.3 and 2.12.12 addresses this through enhanced input validation and arithmetic boundary checking within the Connz request processing logic. These updates ensure that pagination offset and limit values are properly validated before any internal calculations occur, preventing overflow conditions that could lead to server crashes. The mitigation strategy aligns with established security practices for preventing integer overflow vulnerabilities, which are categorized under CWE-190 as "Integer Overflow or Wraparound" and commonly mapped to ATT&CK technique T1499.200 for "Endpoint Denial of Service". Organizations should prioritize updating their NATS Server deployments to these patched versions while implementing monitoring for anomalous connection monitoring request patterns that could indicate exploitation attempts.
This vulnerability demonstrates the importance of proper input validation in high-performance messaging systems where administrative operations can be exposed to potentially malicious clients. The issue highlights how seemingly benign pagination parameters can become attack vectors when not properly bounded, emphasizing the need for comprehensive security testing of all server-side operations that process user-provided data. The fix represents a defensive programming approach that prevents arithmetic overflow conditions by implementing proper range checking and validation before any mathematical operations occur in the connection monitoring response generation pipeline.
The broader implications extend to organizations using NATS Server in production environments where account-scoped monitoring is enabled, as this vulnerability could be exploited to disrupt messaging services without requiring elevated privileges beyond normal client access rights. The remediation process requires careful consideration of deployment schedules and rollback procedures, particularly in distributed systems where multiple NATS Server instances may need coordinated updates. Security teams should monitor for any attempts to exploit this vulnerability through connection monitoring request patterns and implement appropriate network-level controls to prevent unauthorized access to account-scoped monitoring capabilities that could be leveraged for this specific attack vector.