CVE-2025-26855 is a critical SQL injection vulnerability identified in the Articles Calendar extension versions 1.0.0 through 1.0.1.0007 for the Joomla content management system. This vulnerability arises due to improper neutralization of special elements used in SQL commands (CWE-89), allowing an unauthenticated attacker to inject arbitrary SQL code into the backend database queries executed by the extension. Exploiting this flaw requires no authentication or user interaction, and the attack vector is network-based, making it remotely exploitable over the internet. The vulnerability impacts confidentiality, integrity, and availability of the affected systems, as attackers can extract sensitive data, modify or delete data, and potentially execute administrative operations on the database. Given Joomla's widespread use in website management, particularly for small to medium enterprises and public sector websites, this vulnerability poses a significant risk. No known exploits are currently reported in the wild, but the high CVSS score of 9.8 reflects the ease of exploitation combined with the severe consequences of a successful attack. The lack of available patches at the time of publication further increases the urgency for mitigation. This vulnerability highlights the critical need for secure coding practices in Joomla extensions, especially those handling database queries, to prevent injection flaws that can compromise entire web applications.

For European organizations, the impact of CVE-2025-26855 can be substantial. Many European businesses and public institutions rely on Joomla and its extensions for website content management, including event calendars and public information portals. Exploitation could lead to unauthorized disclosure of sensitive customer or citizen data, manipulation of website content, defacement, or complete service disruption. This could result in reputational damage, regulatory penalties under GDPR for data breaches, and operational downtime. The critical nature of the vulnerability means attackers could gain full control over the database backend, potentially pivoting to other internal systems. Organizations in sectors such as government, education, healthcare, and SMEs that use Joomla-based websites are particularly at risk. The absence of a patch increases the window of exposure, necessitating immediate defensive actions to prevent exploitation.

European organizations should take immediate and specific steps to mitigate this vulnerability: 1) Identify all Joomla installations using the Articles Calendar extension versions 1.0.0 to 1.0.1.0007. 2) Disable or uninstall the vulnerable extension until a vendor patch is released. 3) Implement Web Application Firewall (WAF) rules tailored to detect and block SQL injection attempts targeting the extension's endpoints. 4) Conduct thorough input validation and sanitization on any user-supplied data interacting with the calendar functionality, if custom code modifications are possible. 5) Monitor web server and database logs for unusual query patterns or error messages indicative of injection attempts. 6) Restrict database user permissions to the minimum necessary to limit the impact of potential exploitation. 7) Prepare incident response plans to quickly address any signs of compromise. 8) Stay informed on vendor updates and apply patches immediately upon release. These measures go beyond generic advice by focusing on extension-specific controls and proactive detection tailored to this vulnerability.