Can you explain this vulnerability to me?

CVE-2025-14856 is a Server-Side Template Injection (SSTI) vulnerability in the y_project RuoYi framework up to version 4.8.1. It occurs due to improper handling and sanitization of the 'fragment' parameter in the /monitor/cache/getnames endpoint. Attackers can inject malicious Thymeleaf expressions through this parameter, which are then executed by the server's template engine. This allows remote code execution by leveraging Thymeleaf's expression language and access to powerful context objects, enabling attackers to run arbitrary code on the server. [1, 2, 3]

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How can this vulnerability impact me? :

This vulnerability can severely impact the confidentiality, integrity, and availability of your system. An attacker can remotely execute arbitrary code on the server, potentially leading to unauthorized access, data leakage, system compromise, and disruption of services. Since the exploit is publicly available and easy to execute, the risk of exploitation is significant. There are no known effective mitigations currently, making affected systems highly vulnerable. [1, 3]

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How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring and testing the /monitor/cache/getnames endpoint for code injection attempts using specially crafted payloads in the 'fragment' parameter. For example, sending POST requests with payloads like `fragment=|$${#response.getWriter().print(7*7)}|::.x` can reveal if the system executes injected Thymeleaf expressions. Detection commands could include using curl to send such payloads and observe the response for execution results, e.g.: `curl -X POST -d "fragment=|$${#response.getWriter().print(7*7)}|::.x" -H "Content-Type: application/x-www-form-urlencoded" http://target/monitor/cache/getnames`. Additionally, monitoring logs for unusual exceptions or outputs related to this endpoint may help identify exploitation attempts. [3]

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What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include implementing strict whitelist validation for the 'fragment' parameter to allow only predefined safe values, filtering out any input containing Thymeleaf expression syntax, pipe symbols (`|`), or double colons (`::`). Revalidate parameters after URL decoding to prevent encoding bypasses. On the frontend, hardcode the 'fragment' parameter and add request signature verification. Perform content security checks on AJAX responses before DOM insertion. Additionally, disable Thymeleaf expression preprocessing and Spring EL expression compiler in the configuration, restrict accessible context objects and expression types in templates, and consider architectural changes such as separating view rendering from data provision by converting view-returning interfaces to JSON APIs to eliminate template injection risks. If possible, consider replacing the affected component with an alternative product as no known countermeasures are fully effective. [1, 3]

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How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

This vulnerability allows remote code injection leading to potential compromise of confidentiality, integrity, and availability of the affected system. Such a compromise can result in unauthorized access to sensitive data, which may violate compliance requirements under standards like GDPR and HIPAA that mandate protection of personal and health information. However, no explicit mention of compliance impact or regulatory violations is provided in the resources. [1, 3]

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