CVE-2026-46611

Summary

The Glances XML-RPC server (glances -s, implemented in glances/server.py) does not validate the HTTP Host header, leaving it vulnerable to DNS rebinding attacks. CVE-2026-32632 (patched in 4.5.2) added TrustedHostMiddleware to the REST/WebUI server; the MCP server has had equivalent protection since 4.5.1. The XML-RPC server received neither fix and has no allowed-hosts configuration key. Combined with the unrestricted Access-Control-Allow-Origin: * header (see companion advisory for CVE-2026-33533 and its incomplete fix), an attacker can exploit DNS rebinding to exfiltrate the full system monitoring dataset from a victim's browser.

Details

Affected component: glances/server.py — GlancesXMLRPCHandler / GlancesXMLRPCServer

Direct URL (commit 04579778e733d705898a169e049dc84772c852da):

• https://github.com/nicolargo/glances/blob/04579778e733d705898a169e049dc84772c852da/glances/server.py

Contrast — patched backends:

• https://github.com/nicolargo/glances/blob/04579778e733d705898a169e049dc84772c852da/glances/outputs/glances_restful_api.py
• https://github.com/nicolargo/glances/blob/04579778e733d705898a169e049dc84772c852da/glances/outputs/glances_mcp.py

The GlancesXMLRPCHandler class inherits from Python's xmlrpc.server.SimpleXMLRPCRequestHandler and does not override parse_request() to inspect or validate the Host header.

Contrast this with the two other Glances server backends, both of which received host-validation hardening:

REST / WebUI server (glances/outputs/glances_restful_api.py) — patched in 4.5.2:

# glances_restful_api.py
if self.webui_allowed_hosts:
    self._app.add_middleware(
        TrustedHostMiddleware,
        allowed_hosts=self.webui_allowed_hosts,
    )

MCP server (glances/outputs/glances_mcp.py) — protected since 4.5.1:

# glances_mcp.py
TransportSecuritySettings(
    allowed_hosts=self.mcp_allowed_hosts,
    ...
)

XML-RPC server (glances/server.py) — no equivalent exists:

class GlancesXMLRPCHandler(SimpleXMLRPCRequestHandler, GlancesAPI):
    # No Host header check; any Host value is accepted
    rpc_paths = ('/RPC2',)
    ...

There is no xmlrpc_allowed_hosts (or equivalent) configuration key in glances.conf, and the server ignores the Host header on every incoming request.

Confirmed on: x86_64 Linux, Python 3.13, Glances 4.5.5_dev1 (commit 04579778e733d705898a169e049dc84772c852da).

Test results:

| Server type | Host header | HTTP status | Data returned | |-------------|----------------------|-------------|---------------| | XML-RPC | attacker.example.com | 200 OK | Yes — VULNERABLE | | XML-RPC | 127.0.0.1:61209 | 200 OK | Yes (baseline) | | REST API | attacker.example.com | 400 Bad Request | No — patched |

PoC

Attack overview

DNS rebinding breaks the browser Same-Origin Policy by making attacker.example.com temporarily resolve to the target's IP address (e.g. 127.0.0.1). From that point the victim's browser treats the attacker's page as same-origin with http://attacker.example.com:61209/RPC2, forwarding the attacker-controlled Host header to the local Glances XML-RPC server, which accepts it without validation.

Special configuration required

No special glances.conf settings are needed. The vulnerability is present in a default Glances XML-RPC server start (glances -s). For the comparison test (Step 3) the REST server must also be started; that step requires Glances to be installed with web dependencies (pip install "glances[web]").

Step 1 — Start the Glances XML-RPC server

glances -s -p 61209

Step 2 — Confirm the server accepts an arbitrary Host header

curl -s -D - -X POST "http://127.0.0.1:61209/RPC2" \
     -H "Host: attacker.example.com" \
     -H "Content-Type: text/plain" \
     -d '<?xml version="1.0"?>
        …

Summary

The Glances XML-RPC server (glances -s, implemented in glances/server.py) does not validate the HTTP Host header, leaving it vulnerable to DNS rebinding attacks. CVE-2026-32632 (patched in 4.5.2) added TrustedHostMiddleware to the REST/WebUI server; the MCP server has had equivalent protection since 4.5.1. The XML-RPC server received neither fix and has no allowed-hosts configuration key. Combined with the unrestricted Access-Control-Allow-Origin: * header (see companion advisory for CVE-2026-33533 and its incomplete fix), an attacker can exploit DNS rebinding to exfiltrate the full system monitoring dataset from a victim's browser.

Details

Affected component: glances/server.py — GlancesXMLRPCHandler / GlancesXMLRPCServer

Direct URL (commit 04579778e733d705898a169e049dc84772c852da):

• https://github.com/nicolargo/glances/blob/04579778e733d705898a169e049dc84772c852da/glances/server.py

Contrast — patched backends:

• https://github.com/nicolargo/glances/blob/04579778e733d705898a169e049dc84772c852da/glances/outputs/glances_restful_api.py
• https://github.com/nicolargo/glances/blob/04579778e733d705898a169e049dc84772c852da/glances/outputs/glances_mcp.py

The GlancesXMLRPCHandler class inherits from Python's xmlrpc.server.SimpleXMLRPCRequestHandler and does not override parse_request() to inspect or validate the Host header.

Contrast this with the two other Glances server backends, both of which received host-validation hardening:

REST / WebUI server (glances/outputs/glances_restful_api.py) — patched in 4.5.2:

# glances_restful_api.py
if self.webui_allowed_hosts:
    self._app.add_middleware(
        TrustedHostMiddleware,
        allowed_hosts=self.webui_allowed_hosts,
    )

MCP server (glances/outputs/glances_mcp.py) — protected since 4.5.1:

# glances_mcp.py
TransportSecuritySettings(
    allowed_hosts=self.mcp_allowed_hosts,
    ...
)

XML-RPC server (glances/server.py) — no equivalent exists:

class GlancesXMLRPCHandler(SimpleXMLRPCRequestHandler, GlancesAPI):
    # No Host header check; any Host value is accepted
    rpc_paths = ('/RPC2',)
    ...

There is no xmlrpc_allowed_hosts (or equivalent) configuration key in glances.conf, and the server ignores the Host header on every incoming request.

Confirmed on: x86_64 Linux, Python 3.13, Glances 4.5.5_dev1 (commit 04579778e733d705898a169e049dc84772c852da).

Test results:

| Server type | Host header | HTTP status | Data returned | |-------------|----------------------|-------------|---------------| | XML-RPC | attacker.example.com | 200 OK | Yes — VULNERABLE | | XML-RPC | 127.0.0.1:61209 | 200 OK | Yes (baseline) | | REST API | attacker.example.com | 400 Bad Request | No — patched |

PoC

Attack overview

DNS rebinding breaks the browser Same-Origin Policy by making attacker.example.com temporarily resolve to the target's IP address (e.g. 127.0.0.1). From that point the victim's browser treats the attacker's page as same-origin with http://attacker.example.com:61209/RPC2, forwarding the attacker-controlled Host header to the local Glances XML-RPC server, which accepts it without validation.

Special configuration required

No special glances.conf settings are needed. The vulnerability is present in a default Glances XML-RPC server start (glances -s). For the comparison test (Step 3) the REST server must also be started; that step requires Glances to be installed with web dependencies (pip install "glances[web]").

Step 1 — Start the Glances XML-RPC server

glances -s -p 61209

Step 2 — Confirm the server accepts an arbitrary Host header

curl -s -D - -X POST "http://127.0.0.1:61209/RPC2" \
     -H "Host: attacker.example.com" \
     -H "Content-Type: text/plain" \
     -d '<?xml version="1.0"?>
        …

Glances is an open-source system cross-platform monitoring tool. Prior to 4.5.5, the Glances XML-RPC server (glances -s, implemented in glances/server.py) does not validate the HTTP Host header, leaving it vulnerable to DNS rebinding attacks. An attacker can exploit DNS rebinding to exfiltrate the full system monitoring dataset from a victim's browser. This vulnerability is fixed in 4.5.5.

These are all security issues fixed in the glances-common-4.5.5-1.1 package on the GA media of openSUSE Tumbleweed.