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Control panel application (.cpl)

.cpl file signature | application/octet-stream

DOS MZ executableand its descendants (includingNEandPE)

High

Magic Bytes

Offset 0
4D 5A

Sources: Wikipedia, Gary Kessler

All Known Signatures

2 signature variants are documented for .cpl files across multiple sources.

Hex Signature Offset Sources
4D 5A 0 Wikipedia, Gary Kessler
DC DC 0 Gary Kessler

Extension

.cpl

MIME Type

application/octet-stream

Byte Offset

0

Risk Level

High

Validation Code

How to validate .cpl files in Python

Python 
def is_cpl(file_path: str) -> bool:
    """Check if file is a valid CPL by magic bytes."""
    signature = bytes([0x4D, 0x5A])
    with open(file_path, "rb") as f:
        return f.read(2) == signature

How to validate .cpl files in Node.js

Node.js 
function isCPL(buffer: Buffer): boolean {
  const signature = Buffer.from([0x4D, 0x5A]);
  return buffer.subarray(0, 2).equals(signature);
}

How to validate .cpl files in Go

Go 
func IsCPL(data []byte) bool {
    signature := []byte{0x4D, 0x5A}
    if len(data) < 2 {
        return false
    }
    return bytes.Equal(data[:2], signature)
}

API Endpoint

GET /api/v1/cpl
curl https://filesignature.org/api/v1/cpl

See the full API documentation for all endpoints and parameters.

Frequently Asked Questions

What is a .cpl file?

A .cpl file is a Control panel application file. DOS MZ executableand its descendants (includingNEandPE)

What are the magic bytes for .cpl files?

The magic bytes for Control panel application files are 4D 5A at byte offset 0. These bytes uniquely identify the file format regardless of the file extension.

How do I validate a .cpl file?

To validate a .cpl file, read the first bytes of the file and compare them against the known magic bytes (4D 5A) at offset 0. This is more reliable than checking the file extension alone, as extensions can be renamed.

What is the MIME type for .cpl files?

There is no officially registered MIME type for .cpl files. Systems typically use application/octet-stream as a generic fallback when handling this format.

Is it safe to open .cpl files?

Control panel application (.cpl) files are high risk because they can contain executable code. Never open .cpl files from untrusted sources. Always scan with antivirus software, verify the source, and consider running in a sandboxed environment.