CVE-2021-47736
Authenticated Remote Code Execution in CMSimple_XH 1.7.4 Content Editor
Publication date: 2025-12-23
Last updated on: 2025-12-23
Assigner: VulnCheck
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| cmsimple | xh | 1.7.4 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-94 | The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
CVE-2021-47736 is an authenticated remote code execution vulnerability in CMSimple_XH version 1.7.4. It allows administrative users with valid credentials to bypass the CSRF token mechanism and upload malicious PHP files through the content editing functionality. This enables attackers to create a PHP web shell on the server, which can execute arbitrary system commands remotely. [1, 3]
How can this vulnerability impact me? :
This vulnerability can have severe impacts including unauthorized remote execution of system commands on the server hosting CMSimple_XH. An attacker with valid credentials can upload a PHP shell, potentially leading to full server compromise, data theft, service disruption, or further attacks within the network. [1, 3]
How can this vulnerability be detected on my network or system? Can you suggest some commands?
This vulnerability can be detected by checking for the presence of the malicious PHP web shell file (e.g., evil.php) on the server and monitoring for suspicious POST requests to the content editing endpoint that include PHP code payloads. Since exploitation requires authenticated access, reviewing logs for unusual login activity followed by POST requests to '/?file=content' with embedded PHP code can indicate exploitation attempts. Additionally, you can use commands like 'find /path/to/webroot -name evil.php' to locate the web shell file on the server. Network monitoring tools can be configured to alert on HTTP POST requests containing PHP code or unusual parameters targeting the content editing functionality. [1, 3]
What immediate steps should I take to mitigate this vulnerability?
Immediate mitigation steps include restricting administrative access to trusted users only, ensuring strong authentication mechanisms are in place, and monitoring for unauthorized file uploads. Applying patches or updates from CMSimple_XH that address this vulnerability is critical. If patches are not available, consider disabling or restricting the content editing functionality temporarily to prevent exploitation. Additionally, scanning the server for any uploaded malicious PHP files (such as 'evil.php') and removing them is necessary. Implementing web application firewalls (WAF) rules to block suspicious POST requests to the content editing endpoints can also help mitigate exploitation. [1, 3]