CVE-2025-0520 is a critical vulnerability identified in ShowDoc, an open-source documentation platform widely used for collaborative project documentation and knowledge sharing. The vulnerability is classified under CWE-434, which pertains to the unrestricted upload of files with dangerous types. Specifically, this flaw arises due to improper validation of file extensions during the file upload process in ShowDoc versions prior to 2.8.7. Attackers can exploit this weakness by uploading malicious files, particularly PHP scripts, that the application mistakenly accepts and stores without adequate sanitization or restriction. Once uploaded, these PHP files can be executed remotely, enabling an attacker to achieve remote code execution (RCE) on the server hosting ShowDoc. The CVSS 4.0 base score of 9.4 reflects the critical nature of this vulnerability, highlighting its network attack vector (AV:N), low attack complexity (AC:L), no required privileges (PR:L) beyond limited user access, and no user interaction (UI:N). The vulnerability impacts confidentiality, integrity, and availability at a high level, with a broad scope affecting the entire ShowDoc installation. The vulnerability does not require user interaction, and exploitation can be performed remotely, making it highly dangerous. Although no known exploits are currently reported in the wild, the ease of exploitation and the critical impact make it a significant threat. The lack of available patches at the time of publication further exacerbates the risk. Organizations using ShowDoc versions before 2.8.7 are at risk of attackers gaining unauthorized access, executing arbitrary code, potentially leading to data breaches, system compromise, lateral movement within networks, and disruption of documentation services.

For European organizations, the impact of CVE-2025-0520 can be severe, especially for those relying on ShowDoc for internal or external documentation management. Successful exploitation could lead to unauthorized access to sensitive project documentation, intellectual property, and internal communications, compromising confidentiality. Integrity of documentation can be undermined by attackers altering or injecting malicious content, which could mislead teams or clients. Availability of the documentation platform may be disrupted by attackers executing destructive commands or deploying ransomware. Given that ShowDoc is often used in software development, engineering, and project management environments, a compromise could cascade into broader organizational risks, including exposure of credentials, disruption of development pipelines, and damage to organizational reputation. Additionally, organizations in regulated sectors such as finance, healthcare, and critical infrastructure within Europe may face compliance violations and legal consequences if sensitive data is exposed. The vulnerability’s ease of exploitation and remote nature mean that attackers can operate from outside the network perimeter, increasing the risk of widespread attacks. The absence of known exploits in the wild currently provides a window for proactive mitigation, but the critical severity necessitates immediate attention.

1. Immediate Upgrade: Organizations should prioritize upgrading ShowDoc to version 2.8.7 or later, where this vulnerability has been addressed. If an upgrade is not immediately feasible, consider temporary mitigations. 2. File Upload Restrictions: Implement strict server-side validation to restrict allowed file types beyond client-side checks, employing whitelist approaches that only permit safe file extensions. 3. Web Application Firewall (WAF): Deploy or update WAF rules to detect and block attempts to upload PHP or other executable files through ShowDoc endpoints. 4. File Execution Prevention: Configure the web server to disallow execution of uploaded files in the ShowDoc upload directories, for example, by disabling PHP execution in those directories via .htaccess or equivalent configurations. 5. Access Controls: Restrict file upload permissions to trusted users only, and monitor upload activity for anomalies. 6. Network Segmentation: Isolate ShowDoc servers from critical infrastructure to limit lateral movement in case of compromise. 7. Monitoring and Logging: Enable detailed logging of file uploads and access to ShowDoc, and implement alerting for suspicious activities such as uploads of unexpected file types or execution attempts. 8. Incident Response Preparation: Develop and test incident response plans specific to web application compromises, including procedures for containment, eradication, and recovery. 9. Security Awareness: Educate users about the risks of uploading files and encourage reporting of suspicious behavior. These measures, combined with timely patching, will significantly reduce the risk posed by this vulnerability.