CVE-2025-34097 is an unrestricted file upload vulnerability categorized under CWE-434, affecting ProcessMaker versions before 3.5.4. The vulnerability arises from improper validation and handling of uploaded plugin archives, specifically .tar files. An attacker possessing administrative privileges can upload a malicious plugin archive containing arbitrary PHP code. Upon installation of this plugin, the install() method is automatically invoked, which executes the embedded PHP code with the privileges of the web server user. This execution context typically has significant access to the underlying system and application data. The vulnerability is particularly dangerous because it can be chained with CVE-2022-38577, a privilege escalation vulnerability in the user profile page, enabling an attacker starting from a low-privileged account to escalate privileges and achieve full remote code execution on the server. The CVSS 4.0 base score is 8.6, reflecting high severity due to network attack vector, low attack complexity, no required privileges beyond administrative, and no user interaction. The vulnerability does not require social engineering or user interaction, making it easier to exploit once administrative access is obtained. Although no public exploits are currently known, the potential impact includes full system compromise, data theft, service disruption, and lateral movement within the network. The vulnerability affects all versions prior to 3.5.4, and no official patches or mitigation links were provided at the time of publication, emphasizing the need for immediate vendor updates or workarounds.

For European organizations, exploitation of this vulnerability could lead to severe consequences including unauthorized access to sensitive business processes managed by ProcessMaker, data breaches involving personal and corporate data, and potential disruption of critical workflows. Given ProcessMaker's use in business process management and workflow automation, attackers gaining remote code execution could manipulate or halt essential operations, impacting service delivery and compliance with regulations such as GDPR. The ability to chain this vulnerability with a privilege escalation flaw increases the attack surface, allowing attackers to bypass access controls and gain persistent footholds. This could lead to lateral movement within corporate networks, further compromising other systems and data. The impact is particularly critical for sectors relying heavily on ProcessMaker for regulated or sensitive processes, such as finance, healthcare, and government agencies within Europe. Additionally, the compromise of web server privileges can facilitate deployment of ransomware or other malware, amplifying operational and financial damages.

European organizations using ProcessMaker should immediately upgrade to version 3.5.4 or later once available to address this vulnerability. Until patches are applied, restrict administrative privileges strictly to trusted personnel and implement multi-factor authentication to reduce the risk of credential compromise. Employ web application firewalls (WAFs) with custom rules to detect and block suspicious plugin upload attempts, especially those involving .tar archives. Conduct thorough audits of existing plugins and uploaded files to identify and remove any unauthorized or suspicious plugins. Monitor server logs for unusual installation activities or PHP execution patterns indicative of exploitation attempts. Network segmentation should be enforced to limit the exposure of ProcessMaker servers to only necessary internal systems. Additionally, implement strict input validation and file type restrictions at the application level where possible. Regularly review and update access controls and conduct security awareness training focused on privilege misuse. Finally, maintain up-to-date backups and incident response plans to quickly recover from potential compromises.