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This vulnerability in Crafter CMS Studio is a Groovy sandbox bypass that allows authenticated users with developer privileges to execute arbitrary operating system commands. The core flaw resides in the improper control over dynamically-managed code resources within the Groovy scripting engine integration. An attacker can craft a malicious Groovy script or template containing specific elements that exploit the dynamic nature of Groovy’s Meta-Object Protocol (MOP). By inserting these crafted elements, the attacker can manipulate the script’s execution context to bypass the security constraints of the sandbox designed to restrict access to dangerous classes and functions. This manipulation typically involves using metaprogramming features to gain a reference to unrestricted Groovy shell or classloader instances. Once the sandbox restrictions are circumvented, the attacker gains the ability to instantiate and execute Java classes that permit command execution, such as `ProcessBuilder` or Runtime.getRuntime().exec(). This leads to full Remote Code Execution (RCE) on the underlying server with the privileges of the Crafter CMS application process.
Platform: Crafter CMS
Version: 4.0.0 to 4.4.24
Vulnerability : Groovy Sandbox Bypass
Severity: Moderate
date: February 2, 2026
Prediction: Patch released February 2, 2026
What Undercode Say:
curl -s http://target/crafter/studio | grep -i version
// Example malicious Groovy element concept
java.lang.Runtime.getRuntime().exec("id")
How Exploit:
1. Obtain developer credentials.
2. Access script/template editor.
3. Insert malicious Groovy payload.
4. Trigger script execution for RCE.
Protection from this CVE:
Upgrade to version 4.5.0 immediately.
Impact:
Authenticated Remote Code Execution.
Full system compromise.
Privilege escalation possible.
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
