CVE-2026-29839 identifies a Cross-Site Request Forgery (CSRF) vulnerability in the DedeCMS content management system, version 5.7.118, specifically located in the /sys_task_add.php script. CSRF vulnerabilities occur when a web application does not properly verify that requests to perform state-changing operations originate from legitimate users, allowing attackers to craft malicious requests that an authenticated user unknowingly executes. In this case, the vulnerability could allow an attacker to add or manipulate scheduled tasks within the CMS by tricking an authenticated administrator or user with sufficient privileges into visiting a malicious webpage or clicking a crafted link. The absence of a CVSS score suggests this vulnerability is newly published and not yet fully assessed. No public exploits have been reported, indicating limited current exploitation. However, the vulnerability's presence in a core administrative function of DedeCMS poses a risk to the integrity of the CMS environment. The attack requires the victim to be authenticated and interact with attacker-controlled content, limiting the attack surface but still posing a significant risk in environments where users have elevated privileges. The lack of patch links suggests that a fix may not yet be publicly available, emphasizing the need for immediate mitigation strategies.

The primary impact of this CSRF vulnerability is on the integrity of the affected systems, as attackers could manipulate scheduled tasks within the CMS without proper authorization. This could lead to unauthorized content changes, execution of malicious scripts, or disruption of normal CMS operations. Confidentiality and availability impacts are less direct but could occur if attackers leverage task manipulation to deploy further attacks or disrupt services. Organizations relying on DedeCMS for website management, especially those with multiple administrators or users with elevated privileges, face increased risk of unauthorized changes and potential compromise. The requirement for user authentication and interaction reduces the likelihood of widespread automated exploitation but does not eliminate targeted attacks. The absence of known exploits currently limits immediate risk, but the vulnerability could be weaponized once details become widely known. This threat is particularly concerning for organizations that do not implement standard CSRF protections or have weak user access controls.

To mitigate this vulnerability, organizations should implement robust CSRF protections such as synchronizer tokens (CSRF tokens) in all state-changing forms and requests, including those in /sys_task_add.php. Validating the HTTP Referer or Origin headers can provide an additional layer of defense. Administrators should enforce strict user access controls and limit the number of users with permissions to add or modify scheduled tasks. Monitoring and logging administrative actions can help detect suspicious activity. Until an official patch is released, consider restricting access to the affected endpoint via web application firewalls (WAFs) or network controls. Educate users, especially administrators, about the risks of clicking untrusted links while authenticated to the CMS. Regularly check for updates from the DedeCMS vendor and apply patches promptly once available. Conduct security assessments to identify other potential CSRF vulnerabilities within the CMS environment.