CVE-2020-26167 is a critical vulnerability identified in FUEL CMS versions 11.4.12 and earlier. The flaw resides in the page preview feature of the CMS, which is intended to allow users to preview content before publishing. However, due to improper access controls, this feature can be exploited by an anonymous attacker to take complete ownership of any user account within the system, including those with administrative privileges. This means that without any authentication or prior access, an attacker can escalate their privileges to that of an administrator, gaining full control over the CMS environment. The vulnerability likely stems from insufficient validation or authorization checks in the page preview functionality, allowing the attacker to manipulate session or user context data to impersonate other users. No official patch or vendor information is provided in the data, and no known exploits have been reported in the wild as of the publication date. The lack of a CVSS score indicates that the vulnerability has not been formally scored, but the nature of the flaw suggests a severe security risk. Given that FUEL CMS is a content management system, exploitation could lead to unauthorized content modification, data theft, defacement, or further pivoting into the hosting infrastructure.

For European organizations using FUEL CMS, this vulnerability poses a significant risk to the confidentiality, integrity, and availability of their web content and associated data. An attacker gaining administrative access can manipulate website content, inject malicious code, steal sensitive data, or disrupt services. This could lead to reputational damage, legal liabilities under GDPR due to data breaches, and operational downtime. Organizations in sectors such as government, education, media, and e-commerce that rely on FUEL CMS for their web presence are particularly vulnerable. The ability for an anonymous user to fully compromise accounts without authentication greatly increases the attack surface and lowers the barrier for exploitation. Even though no known exploits are reported, the vulnerability's existence since at least 2020 means unpatched systems remain at risk. The impact extends beyond the CMS itself, as attackers could leverage administrative access to move laterally within the network or deploy ransomware or other malware.

Immediate mitigation steps include upgrading FUEL CMS to a version where this vulnerability is patched; however, no patch links are provided, so organizations should consult the official FUEL CMS repositories or community for updates. In the absence of an official patch, organizations should disable or restrict access to the page preview feature, especially for anonymous users. Implementing web application firewalls (WAFs) with rules to detect and block suspicious requests targeting the preview functionality can provide temporary protection. Conduct thorough access control reviews and ensure that session management and user impersonation mechanisms are secure. Regularly audit CMS user accounts for unauthorized changes and monitor logs for unusual activity. Additionally, organizations should isolate the CMS environment from critical internal networks to limit lateral movement in case of compromise. Finally, organizations should prepare incident response plans specifically addressing CMS compromises.