CVE-2026-120046 in Nezha
Summary
by MITRE • 10/30/2026
Nezha 2.0.0 before 2.4.0 contains a NULL pointer dereference vulnerability in ServiceSentinel.loadTodayStats that allows authenticated users to crash the dashboard by deleting a service. Attackers can delete their own service via POST /api/v1/batch-delete/service, leaving orphaned service_histories rows that crash the non-TSDB dashboard on its next startup until removed manually.
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Analysis
by VulDB Data Team • 10/30/2026
The vulnerability identified in Nezha versions prior to 2.4.0 represents a critical stability issue rooted in improper input validation and resource management within the ServiceSentinel component. Specifically, the flaw resides in the loadTodayStats function, which is responsible for aggregating monitoring data from historical records stored in the database. When an authenticated user executes a request to delete their own service via the POST /api/v1/batch-delete/service endpoint, the system performs the deletion of the primary service record but fails to adequately handle or clean up associated dependent records known as service_histories. This incomplete cleanup process results in orphaned rows remaining in the database that reference non-existent parent services or contain null values where valid references are expected.
From a technical perspective, this scenario constitutes a NULL pointer dereference vulnerability, which is categorized under CWE-476: NULL Pointer Dereference. The application logic assumes that when loading today's statistics for display on the dashboard, all referenced service records will exist and be properly initialized. However, due to the orphaned history rows created by the deletion process, the code attempts to access properties or methods of a null object reference during the initialization phase. This logical error triggers an unhandled exception within the application runtime environment. Because this specific function is invoked during the startup sequence of the non-Time Series Database (TSDB) dashboard mode, the crash occurs immediately upon service launch, preventing the monitoring interface from becoming available to administrators and users alike.
The operational impact of this vulnerability is significant in terms of availability and system reliability. Although the attack requires authentication, meaning it cannot be exploited by unauthenticated external actors without prior compromise of credentials, it poses a severe risk to internal operations or any scenario where user accounts are compromised. An attacker with valid access can deliberately crash the monitoring dashboard simply by deleting their monitored service. The resulting denial of service persists until an administrator manually intervenes to clean up the orphaned database records and restart the application. This creates a persistent availability gap that disrupts visibility into infrastructure health, potentially masking other ongoing security incidents or performance issues while the system is down for manual remediation.
This vulnerability aligns with several entries in the MITRE ATT&CK framework, particularly those related to Impact tactics such as T1499: Endpoint Denial of Service and T1529: System Shutdown/Reboot if applied broadly, though here it manifests specifically through application-level instability rather than OS-level shutdown. It also reflects weaknesses associated with CWE-608: Extension Function Error in the context of how external data sources are handled without sufficient validation. The root cause lies in a failure to implement proper referential integrity constraints or transactional rollback mechanisms during the deletion process, allowing inconsistent states to persist in the database schema.
To mitigate this vulnerability and prevent recurrence, immediate action must be taken by upgrading Nezha to version 2.4.0 or later, where the developers have addressed the logic flaw within ServiceSentinel.loadTodayStats. For environments that cannot immediately upgrade, administrators should implement manual database maintenance procedures to identify and remove orphaned service_history records associated with deleted services. Additionally, implementing stricter input validation at the API layer to ensure cascading deletes are handled atomically can prevent this state inconsistency from occurring in future versions or custom deployments. Enforcing robust transactional boundaries around deletion operations ensures that either all related data is removed successfully or no changes are applied, thereby maintaining database integrity and preventing null reference exceptions during subsequent application startup sequences.