Impact

This vulnerability affects applications that:

• Use the ImageMagick handler for image processing (imagick as the image library)
• AND either:
  • Allow file uploads with user-controlled filenames and process uploaded images using the resize() method
  • OR use the text() method with user-controlled text content or options

An attacker can:

• Upload a file with a malicious filename containing shell metacharacters that get executed when the image is processed
• OR provide malicious text content or options that get executed when adding text to images

Patches

Upgrade to v4.6.2 or later.

Workarounds

• Switch to the GD image handler (gd, the default handler), which is not affected by either vulnerability
• For file upload scenarios: Instead of using user-provided filenames, generate random names to eliminate the attack vector with getRandomName() when using the move() method, or use the store() method, which automatically generates safe filenames
• For text operations: If you must use ImageMagick with user-controlled text, sanitize the input to only allow safe characters: preg_replace('/[^a-zA-Z0-9\s.,!?-]/', '', $text) and validate/restrict text options

References

• OWASP Command Injection Prevention
• CWE-78: OS Command Injection