CVE-2026-47724 in nebula-mesh
Summary
by MITRE • 07/24/2026
nebula-mesh is a self-hosted control plane for Slack Nebula mesh virtual private network. Prior to version 0.3.4, the `/api/v1/*` route surface trusts the bearer token alone for authorisation on most endpoints. The codebase itself admits this at `internal/api/hosts.go:384`: "API trusts the bearer token for authorisation; per-CA ownership is enforced only in the Web layer." The Web UI gates state-changing routes through `loadAccessibleCA` (`internal/web/cas.go`); CA-management endpoints in `internal/api/cas.go` ALSO have proper `canAccessCA` gates. The gap is on the host, network, firewall, mobile-bundle, and most operator endpoints. Combined with the per-operator CA model from ADR 0002, this gives any non-admin operator API key broad cross-tenant access — instant privilege escalation in the worst case. Version 0.3.4 fixes the issue.
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Analysis
by VulDB Data Team • 07/24/2026
The nebula-mesh vulnerability stems from a critical authorization flaw in the control plane's API implementation that affects versions prior to 0.3.4. This issue represents a classic case of insufficient access control where bearer tokens alone are trusted for authentication without proper authorization checks across multiple API endpoints. The vulnerability manifests specifically within the `/api/v1/*` route structure where the system incorrectly assumes that token validation is sufficient for access control, creating a dangerous gap in the security model.
The technical implementation reveals a fundamental architectural weakness in how the system handles privilege separation between different levels of access. While the web UI correctly implements `loadAccessibleCA` checks to gate state-changing routes, and CA management endpoints properly enforce `canAccessCA` validations, the host, network, firewall, mobile-bundle, and most operator endpoints lack these critical authorization gates. This inconsistency creates a scenario where any authenticated user with a non-admin operator API key can potentially access and modify resources across multiple tenants within the mesh network.
The per-operator CA model introduced through ADR 0002 exacerbates this vulnerability by establishing a cross-tenant access pattern that becomes dangerous when combined with the insufficient authorization checks. This architectural decision allows operators to manage specific CAs while maintaining the assumption that token-based authentication alone provides adequate security boundaries. The gap in implementation means that legitimate API requests can bypass proper tenant isolation, creating immediate privilege escalation opportunities. According to CWE-285, this represents an Authorization Bypass Through User-Controlled Key vulnerability where user-controlled tokens are trusted without proper authorization validation.
The operational impact of this vulnerability is severe as it enables unauthorized access to critical network infrastructure components including host configurations, network policies, firewall rules, and mobile bundle deployments. An attacker with a valid operator API key could manipulate resources across multiple tenants, potentially disrupting network operations, compromising security policies, or gaining access to sensitive configuration data belonging to other organizations using the same mesh infrastructure.
The fix implemented in version 0.3.4 addresses this by ensuring consistent authorization checks across all API endpoints, particularly closing the gap that existed between the web UI's proper validation and the API layer's insufficient protection. This remediation aligns with ATT&CK technique T1078.004 which covers Valid Accounts with the specific emphasis on credential exposure and unauthorized access to systems through compromised or improperly validated authentication tokens.
This vulnerability demonstrates the importance of consistent security implementation across all layers of an application architecture, particularly in multi-tenant environments where proper isolation is critical for maintaining security boundaries. The issue highlights how even well-intentioned architectural decisions can create security holes when not properly implemented across all system components. Organizations using nebula-mesh should immediately upgrade to version 0.3.4 or later to ensure that authorization controls are properly enforced across all API endpoints, preventing unauthorized cross-tenant access and maintaining the integrity of their mesh network configurations.