CVE-2023-30331 in beetl
Summary
by MITRE • 05/04/2023
An issue in the render function of beetl v3.15.0 allows attackers to execute server-side template injection (SSTI) via a crafted payload.
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Analysis
by VulDB Data Team • 07/13/2025
The vulnerability identified as CVE-2023-30331 represents a critical server-side template injection flaw within the beetl template engine version 3.15.0. This issue resides in the render function implementation where inadequate input validation and sanitization permits malicious actors to inject arbitrary template code that gets executed on the server. The vulnerability stems from the template engine's failure to properly escape or filter user-supplied data before incorporating it into template rendering processes. Attackers can exploit this weakness by crafting malicious payloads that leverage the template engine's syntax to execute unauthorized operations, potentially leading to complete system compromise. The flaw demonstrates a classic lack of proper context-aware escaping mechanisms that should prevent template code from being interpreted when user input is processed within template contexts.
The technical exploitation of this vulnerability follows a pattern consistent with server-side template injection attacks as classified under CWE-94, which specifically addresses the execution of arbitrary code through improper handling of template parameters. The attack vector involves supplying malicious input that bypasses the template engine's security controls, allowing attackers to execute arbitrary commands or access sensitive system resources. When the render function processes user-provided data without proper sanitization, the template engine interprets attacker-controlled content as template syntax rather than literal text, enabling code execution. This vulnerability directly impacts the integrity and confidentiality of applications relying on beetl for template rendering, as it allows for arbitrary code execution that can be leveraged to escalate privileges, access databases, or perform other malicious activities within the application's operational environment.
The operational impact of CVE-2023-30331 extends beyond simple code execution to encompass potential data breaches, system compromise, and business disruption. Organizations utilizing beetl v3.15.0 in production environments face significant risk exposure, as the vulnerability can be exploited remotely without authentication requirements. The attack surface includes any application component that accepts user input and passes it through the beetl template rendering pipeline, making it particularly dangerous for web applications, content management systems, and any platform processing user-generated content. Security teams must consider that this vulnerability aligns with ATT&CK technique T1059.001 for command and script interpreter execution, as successful exploitation enables attackers to execute arbitrary commands on the affected system. The impact assessment should include potential for lateral movement within network environments, data exfiltration, and establishment of persistent access through the compromised template rendering functionality.
Mitigation strategies for CVE-2023-30331 require immediate action to address the root cause through proper input validation and sanitization. Organizations should prioritize upgrading to beetl versions that have addressed this vulnerability, as the maintainers have released patched releases containing proper template escaping mechanisms. Security measures should include implementing strict input validation at all points where user data enters the template processing pipeline, applying context-aware escaping techniques, and establishing proper template security policies. Additional protective measures include deploying web application firewalls to detect and block suspicious template injection patterns, implementing least privilege access controls for template rendering components, and conducting thorough code reviews to identify other potential template injection vulnerabilities. The remediation process should follow security best practices outlined in OWASP Top 10 and NIST cybersecurity frameworks, ensuring comprehensive protection against similar vulnerabilities in other template engines and application components. Regular security assessments and penetration testing should be conducted to verify that the implemented fixes effectively prevent exploitation attempts and maintain system integrity against evolving attack vectors.