CVE-2026-46608 in glances
Summary
by MITRE • 06/25/2026
Glances is an open-source system cross-platform monitoring tool. Prior to 4.5.5, the Glances XML-RPC server (glances -s) introduced a configurable CORS origin list in version 4.5.3 as a mitigation for CVE-2026-33533. However, the implementation silently falls back to Access-Control-Allow-Origin: * whenever cors_origins contains more than one entry. An operator who configures an explicit two-entry allowlist (e.g. two internal dashboard origins) intending to restrict browser access instead receives the unrestricted wildcard. A malicious web page served from any origin can issue a CORS simple request to /RPC2 and read the full system monitoring dataset without the victim's knowledge. This vulnerability is fixed in 4.5.5.
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Analysis
by VulDB Data Team • 06/26/2026
The Glances monitoring tool presents a critical cross-origin resource sharing vulnerability that emerged from an overly permissive fallback mechanism in its XML-RPC server implementation. This issue affects versions prior to 4.5.5 and specifically targets the CORS origin validation logic introduced in version 4.5.3 as a response to CVE-2026-33533. The vulnerability stems from a fundamental flaw in how the system handles multiple origin entries within the cors_origins configuration parameter, creating an unexpected security regression that undermines the intended access controls.
The technical implementation error occurs when operators configure explicit CORS allowlists containing two or more origins, which should restrict access to only those specific domains. However, the flawed logic silently reverts to a wildcard configuration Access-Control-Allow-Origin: * whenever multiple entries are present in the cors_origins list. This behavior represents a clear violation of security by design principles and creates an automatic bypass mechanism that renders the explicit origin restrictions ineffective. The vulnerability manifests through a simple CORS preflight request to the /RPC2 endpoint, allowing any web page regardless of its origin to access the complete system monitoring dataset without user knowledge or consent.
The operational impact of this vulnerability is severe as it enables remote attackers to execute unauthorized data exfiltration against systems running vulnerable Glances versions. The attack vector requires no authentication or privileged access, making it particularly dangerous in environments where monitoring tools are exposed to untrusted networks. An attacker can craft a malicious web page that automatically issues CORS requests to the Glances XML-RPC server, harvesting sensitive system information including process lists, resource utilization metrics, network statistics, and other monitoring data that could reveal critical infrastructure details. This capability directly aligns with ATT&CK technique T1567.002 for "Exfiltration Over Web Service" and represents a classic example of insecure cross-origin resource sharing implementation.
This vulnerability maps to CWE-693 Protection Mechanism Failure, specifically highlighting the weakness in how the system validates and enforces access controls. The implementation flaw demonstrates poor security configuration management where a defensive measure intended to address one vulnerability inadvertently creates a more severe security regression. Organizations using Glances in production environments face significant risk exposure, particularly when monitoring servers are accessible from external networks or when the tool is deployed in multi-tenant environments. The silent fallback mechanism makes detection particularly challenging as administrators may believe their CORS restrictions are properly enforced while the system operates with unrestricted access permissions.
The recommended mitigation strategy involves immediate deployment of Glances version 4.5.5, which resolves the problematic fallback behavior and properly enforces explicit CORS origin lists. System administrators should also implement additional network-level controls such as firewall rules to restrict access to the XML-RPC server port, particularly when the tool is deployed in environments where untrusted origins might exist. Configuration reviews should ensure that only necessary origins are included in cors_origins lists, and that the system operates behind appropriate network segmentation. Organizations should consider implementing monitoring for unusual patterns of access to the RPC2 endpoint, as unauthorized access attempts may indicate exploitation attempts. The fix implemented in version 4.5.5 addresses the root cause by properly handling multiple origin entries without falling back to wildcard configurations, thereby restoring the intended security controls and maintaining the tool's utility while preventing unauthorized data access.