CVE-2026-86118 in Gonic
Summary
by MITRE • 09/05/2026
gonic versions before 0.22.0 fail to validate administrator privileges in the startScan endpoint, allowing any authenticated user to trigger media library rescans. Attackers can repeatedly call the startScan endpoint to force CPU and I/O-intensive filesystem operations, causing denial of service on multi-user instances.
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Analysis
by VulDB Data Team • 09/05/2026
The vulnerability identified in Gonic versions prior to 0.22.0 represents a critical authorization failure within the application's media library management subsystem. Specifically, the flaw resides in the startScan endpoint, which is designed to initiate a deep rescan of the server's file system to update metadata and track new or modified audio files. In vulnerable implementations, this endpoint lacks proper access control checks to verify that the requesting user possesses administrator privileges. Consequently, any authenticated user, regardless of their role or permission level within the application, can invoke this function. This breakdown in privilege separation allows standard users to execute operations that are strictly intended for system administrators, fundamentally undermining the security model of multi-user deployments where resource allocation and administrative actions must be tightly controlled.
The operational impact of this vulnerability is primarily centered on denial of service through resource exhaustion. The media library rescan process is inherently computationally expensive and I/O intensive, as it requires traversing directory structures, reading file headers, parsing metadata tags, and updating database records for potentially thousands or millions of files. When an attacker repeatedly calls the startScan endpoint without authorization limits or rate limiting mechanisms in place, they can force the server to perform these heavy operations continuously. This behavior consumes significant CPU cycles and saturates disk input/output bandwidth, leading to severe performance degradation. In a multi-user environment, this resource starvation affects all connected users, rendering the service unusable for legitimate activities such as streaming audio or managing playlists, effectively achieving a denial of service condition without requiring any external network-based attack vectors like flooding.
From a technical classification perspective, this vulnerability aligns with CWE-269, which covers Improper Privilege Management and specifically the failure to enforce administrative privileges on sensitive functions. The exploitation technique involves abusing an authenticated session to perform unauthorized actions, mapping directly to MITRE ATT&CK techniques related to Defense Evasion or Impact via resource consumption. While Gonic is primarily a music server application rather than a traditional web service, the principle remains consistent with common web application vulnerabilities where API endpoints are exposed without adequate role-based access control checks. The lack of input validation regarding user roles allows low-privilege accounts to escalate their effective permissions simply by invoking specific administrative APIs.
Mitigation for this vulnerability requires an immediate upgrade to Gonic version 0.22.0 or later, where the authorization logic has been corrected to enforce strict administrator-only access on the startScan endpoint. For environments that cannot immediately patch due to operational constraints, temporary mitigations should focus on network-level controls and application configuration. Implementing rate limiting at a reverse proxy layer such as Nginx or Traefik can restrict the frequency of requests sent to the scan endpoints by any single IP address or user session. Additionally, administrators should review their deployment architecture to ensure that administrative interfaces are not exposed directly to untrusted networks without additional authentication layers. Enforcing strong password policies and multi-factor authentication for all accounts reduces the likelihood of an attacker obtaining valid credentials in the first place, thereby limiting the attack surface available for this specific exploitation path.