CVE-2023-26001 is a security vulnerability classified as CWE-79, which corresponds to Improper Neutralization of Input During Web Page Generation, commonly known as Cross-site Scripting (XSS). This specific vulnerability affects the Marchetti Design Next Event Calendar product, versions up to 1.2. The vulnerability is a Stored XSS flaw, meaning that malicious input submitted by an attacker is stored persistently by the application and later rendered in web pages viewed by other users without proper sanitization or encoding. This allows attackers to inject arbitrary client-side scripts into the web pages generated by the calendar application. When other users access the affected pages, the malicious scripts execute in their browsers within the security context of the vulnerable site. The CVSS v3.1 base score for this vulnerability is 5.9, indicating a medium severity level. The vector string (AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L) reveals that the attack can be performed remotely over the network with low attack complexity, but requires high privileges and user interaction. The scope is changed (S:C), meaning the vulnerability affects resources beyond the vulnerable component. The impact includes low confidentiality, integrity, and availability impacts, but the stored nature of the XSS can enable persistent attacks such as session hijacking, defacement, or distribution of malware. No known exploits in the wild have been reported, and no official patches or updates have been linked yet. The vulnerability was published on June 6, 2025, and was assigned by Patchstack. The Next Event Calendar is a web-based event management tool, often integrated into websites to display event schedules and details.

For European organizations using the Marchetti Design Next Event Calendar, this vulnerability poses a risk of persistent cross-site scripting attacks that can compromise user accounts, steal session tokens, or manipulate displayed content. Given the stored nature of the XSS, attackers can embed malicious scripts that affect multiple users over time, potentially leading to data leakage or reputational damage. Organizations in sectors with high web presence such as education, event management, cultural institutions, and small to medium enterprises that rely on this calendar plugin are particularly at risk. The requirement for high privileges to exploit somewhat limits the attack surface to users with elevated access, but social engineering or insider threats could facilitate exploitation. The vulnerability's impact on confidentiality, integrity, and availability is low to medium but can be leveraged as part of a broader attack chain. Additionally, the scope change indicates that the vulnerability could affect other components or user sessions beyond the calendar itself, increasing potential damage. Since no patches are currently available, organizations must be vigilant to prevent exploitation.

1. Restrict access to the Next Event Calendar administrative interface to trusted users only, minimizing the number of users with high privileges who can input event data. 2. Implement strict input validation and output encoding on all user-supplied data fields within the calendar application, especially those that render HTML content. 3. Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts and reduce the impact of potential XSS payloads. 4. Monitor web application logs and user activity for suspicious inputs or unusual behavior indicative of attempted XSS exploitation. 5. If feasible, temporarily disable or replace the Next Event Calendar plugin with an alternative event management solution until an official patch is released. 6. Educate privileged users about the risks of injecting untrusted content and enforce strong authentication and session management controls. 7. Use web application firewalls (WAF) with rules targeting XSS attack patterns to provide an additional layer of defense. 8. Regularly check for updates from Marchetti Design and apply patches promptly once available.