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How the CVE Works:
The vulnerability exists in phpThumb’s `gif_outputAsJpeg` function, which processes GIF-to-JPEG conversions. Attackers can inject malicious OS commands via crafted input parameters, exploiting insufficient input sanitization. The function passes user-controlled data directly to shell-executed commands (e.g., ImageMagick), enabling arbitrary command execution. The flaw stems from improper escaping of filenames or options in phpthumb.gif.php, allowing attackers to chain commands via shell metacharacters (e.g., ;, &&). Fixed in version 1.7.23-202506081709 by validating and escaping user inputs before shell execution.
DailyCVE Form:
Platform: phpThumb
Version: ≤1.7.23
Vulnerability: Command Injection
Severity: Moderate
Date: 2025-07-11
Prediction: Patch expected by 2025-07-25
What Undercode Say:
Exploit PoC (simplified): curl "http://target/phpthumb.php?src=test.gif%3Bcat%20/etc/passwd" Detection: grep -r "gif_outputAsJpeg" /path/to/phpThumb Mitigation test: php -l phpthumb.gif.php | grep "escapeshellarg"
How Exploit:
- Crafted HTTP request with shell metacharacters in `src` parameter.
- Leverages insecure `exec()` or `system()` calls in GIF processing.
Protection from this CVE:
- Update to phpThumb ≥1.7.23-202506081709.
- Disable shell execution for image processing.
- Apply input validation using
escapeshellarg().
Impact:
- Remote code execution (RCE) under web server privileges.
- Unauthorized filesystem access or data exfiltration.
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
