Affected: Homebrew: glances

Glances is an open-source system cross-platform monitoring tool. Glances recently added DNS rebinding protection for the MCP endpoint, but prior to version 4.5.2, the main REST/WebUI FastAPI application still accepts arbitrary `Host` headers and does not apply `TrustedHostMiddleware` or an equivalent host allowlist. As a result, the REST API, WebUI, and token endpoint remain reachable through attacker-controlled domains in classic DNS rebinding scenarios. Once the victim browser has rebound the attacker domain to the Glances service, same-origin policy no longer protects the API because the browser considers the rebinding domain to be the origin. This is a distinct issue from the previously reported default CORS weakness. CORS is not required for exploitation here because DNS rebinding causes the victim browser to treat the malicious domain as same-origin with the rebinding target. Version 4.5.2 contains a patch for the issue.

Glances is an open-source system cross-platform monitoring tool. Glances recently added DNS rebinding protection for the MCP endpoint, but prior to version 4.5.2, the main REST/WebUI FastAPI application still accepts arbitrary `Host` headers and does not apply `TrustedHostMiddleware` or an equivalent host allowlist. As a result, the REST API, WebUI, and token endpoint remain reachable through attacker-controlled domains in classic DNS rebinding scenarios. Once the victim browser has rebound the attacker domain to the Glances service, same-origin policy no longer protects the API because the browser considers the rebinding domain to be the origin. This is a distinct issue from the previously reported default CORS weakness. CORS is not required for exploitation here because DNS rebinding causes the victim browser to treat the malicious domain as same-origin with the rebinding target. Version 4.5.2 contains a patch for the issue.

Affected: PyPI: Glances

## Summary

Glances recently added DNS rebinding protection for the MCP endpoint, but the main REST/WebUI FastAPI application still accepts arbitrary `Host` headers and does not apply `TrustedHostMiddleware` or an equivalent host allowlist.

As a result, the REST API, WebUI, and token endpoint remain reachable through attacker-controlled domains in classic DNS rebinding scenarios. Once the victim browser has rebound the attacker domain to the Glances service, same-origin policy no longer protects the API because the browser considers the rebinding domain to be the origin.

This is a distinct issue from the previously reported default CORS weakness. CORS is not required for exploitation here because DNS rebinding causes the victim browser to treat the malicious domain as same-origin with the rebinding target.

## Details

The MCP endpoint now has explicit host-based transport security:

```python # glances/outputs/glances_mcp.py self.mcp_allowed_hosts = ["localhost", "127.0.0.1"] ... return TransportSecuritySettings( allowed_hosts=allowed_hosts, allowed_origins=allowed_origins, ) ```

However, the main FastAPI application for REST/WebUI/token routes is initialized without any host validation middleware:

```python # glances/outputs/glances_restful_api.py self._app = FastAPI(default_response_class=GlancesJSONResponse) ... self._app.add_middleware( CORSMiddleware, allow_origins=config.get_list_value('outputs', 'cors_origins', default=["*"]), allow_credential…

glances-common-4.5.2-1.1 on GA media

Affected: PyPI: glances

Glances is an open-source system cross-platform monitoring tool. Glances recently added DNS rebinding protection for the MCP endpoint, but prior to version 4.5.2, the main REST/WebUI FastAPI application still accepts arbitrary `Host` headers and does not apply `TrustedHostMiddleware` or an equivalent host allowlist. As a result, the REST API, WebUI, and token endpoint remain reachable through attacker-controlled domains in classic DNS rebinding scenarios. Once the victim browser has rebound the attacker domain to the Glances service, same-origin policy no longer protects the API because the browser considers the rebinding domain to be the origin. This is a distinct issue from the previously reported default CORS weakness. CORS is not required for exploitation here because DNS rebinding causes the victim browser to treat the malicious domain as same-origin with the rebinding target. Version 4.5.2 contains a patch for the issue.

Affected: Ubuntu:Pro:16.04:LTS: glances, Ubuntu:Pro:18.04:LTS: glances, Ubuntu:Pro:20.04:LTS: glances, Ubuntu:22.04:LTS: glances, Ubuntu:24.04:LTS: glances, Ubuntu:25.10: glances, Ubuntu:26.04:LTS: glances

Glances is an open-source system cross-platform monitoring tool. Glances recently added DNS rebinding protection for the MCP endpoint, but prior to version 4.5.2, the main REST/WebUI FastAPI application still accepts arbitrary `Host` headers and does not apply `TrustedHostMiddleware` or an equivalent host allowlist. As a result, the REST API, WebUI, and token endpoint remain reachable through attacker-controlled domains in classic DNS rebinding scenarios. Once the victim browser has rebound the attacker domain to the Glances service, same-origin policy no longer protects the API because the browser considers the rebinding domain to be the origin. This is a distinct issue from the previously reported default CORS weakness. CORS is not required for exploitation here because DNS rebinding causes the victim browser to treat the malicious domain as same-origin with the rebinding target. Version 4.5.2 contains a patch for the issue.