CVE-2026-2551 is a path traversal vulnerability identified in ZenTao, an open-source project management and bug tracking software, affecting all versions up to 21.7.8. The vulnerability resides in the delete function within the file editor/control.php script of the Backup Handler component. Specifically, the flaw arises from improper sanitization of the fileName parameter, which an attacker can manipulate to traverse directories and access or delete arbitrary files on the server. This can lead to unauthorized disclosure or modification of sensitive files, potentially compromising system integrity and confidentiality. The vulnerability is remotely exploitable without requiring user interaction, but it requires low privileges (PR:L), indicating that an attacker must have some level of authenticated access to the system. The CVSS 4.0 base score of 5.3 reflects a medium severity, with network attack vector, low attack complexity, no user interaction, and limited impact on confidentiality, integrity, and availability. Although no exploits have been observed in the wild, the public disclosure of the vulnerability increases the likelihood of exploitation attempts. The vulnerability's exploitation could disrupt backup processes or enable attackers to manipulate critical files, impacting business continuity and data security. ZenTao is widely used in software development environments, making this vulnerability relevant to organizations relying on it for project tracking and management.

For European organizations, exploitation of CVE-2026-2551 could lead to unauthorized access or deletion of critical files managed by ZenTao, resulting in potential data loss, leakage of sensitive project information, or disruption of development workflows. This could affect confidentiality by exposing internal project data, integrity by allowing unauthorized file deletions or modifications, and availability by potentially disrupting backup operations or causing application instability. Organizations in sectors with strict data protection requirements, such as finance, healthcare, and government, may face compliance risks if sensitive data is exposed. Additionally, the disruption of project management tools can delay critical software development and deployment cycles, impacting business operations. Given the remote exploitability and low attack complexity, threat actors could leverage this vulnerability to gain footholds in corporate networks or escalate privileges. The medium severity indicates a moderate but non-trivial risk, warranting timely remediation to prevent exploitation.

To mitigate CVE-2026-2551, organizations should immediately plan to upgrade ZenTao to a version that patches this vulnerability once available from the vendor. Until patches are applied, restrict access to the vulnerable delete function by implementing network-level controls such as IP whitelisting or VPN-only access to the ZenTao management interface. Employ web application firewalls (WAFs) with custom rules to detect and block path traversal attempts targeting the fileName parameter. Conduct thorough input validation and sanitization on all user-supplied parameters, especially those interacting with file system operations, to prevent directory traversal. Review and tighten user privilege assignments to ensure that only trusted users have access to functions that can delete files. Regularly audit logs for suspicious activity related to file deletions or access attempts. Finally, maintain up-to-date backups of critical data and test restoration procedures to minimize impact in case of successful exploitation.