CVE-2025-49436 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 vulnerability affects the thiudis Custom Menu product, specifically versions up to 1.8. The flaw allows an attacker to inject malicious scripts that are stored persistently (Stored XSS) and later executed in the context of users visiting the affected web pages. Stored XSS occurs when malicious input is saved by the application and then rendered without proper sanitization or encoding, enabling attackers to execute arbitrary JavaScript code in victims' browsers. The CVSS v3.1 base score is 6.5, indicating a medium severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L) reveals that the attack can be performed remotely over the network (AV:N) with low attack complexity (AC:L), requires the attacker to have some privileges (PR:L), and requires user interaction (UI:R). The scope is changed (S:C), meaning the vulnerability affects components beyond the initially vulnerable component. The impact affects confidentiality, integrity, and availability to a low degree (C:L, I:L, A:L). No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability was reserved in June 2025 and published in August 2025. The vulnerability arises from insufficient input validation or output encoding in the Custom Menu component, allowing malicious payloads to be stored and executed when rendered in users' browsers. This can lead to session hijacking, credential theft, defacement, or distribution of malware through the compromised web interface.

For European organizations using thiudis Custom Menu, this vulnerability poses a risk of client-side attacks that can compromise user sessions and data confidentiality. Stored XSS can be leveraged to steal authentication cookies, perform actions on behalf of users, or deliver further malware payloads. Organizations in sectors with sensitive data or regulatory requirements (e.g., finance, healthcare, government) could face data breaches or compliance violations if exploited. The medium severity and requirement for some privileges and user interaction reduce the likelihood of widespread automated exploitation but do not eliminate targeted attacks. The changed scope indicates that the impact could extend beyond the immediate component, potentially affecting other integrated systems or user roles. Since no patches are currently available, organizations must be vigilant in monitoring and mitigating risks. The absence of known exploits suggests that attackers may not yet have weaponized this vulnerability, but proactive measures are critical to prevent future exploitation. The impact on availability is low but could manifest as denial of service through script execution or defacement. Confidentiality and integrity impacts, while low, are significant in environments where user trust and data protection are paramount.

1. Immediate mitigation should include implementing strict input validation and output encoding for all user-supplied data rendered by the Custom Menu component. Employ context-aware encoding (e.g., HTML entity encoding) to neutralize scripts. 2. Apply the principle of least privilege to limit user roles capable of injecting content into the Custom Menu, reducing the risk of privilege escalation. 3. Use Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers accessing the affected application. 4. Monitor application logs and user activity for unusual behavior indicative of XSS exploitation attempts. 5. Engage with the vendor (thiudis) for timely patches or updates addressing this vulnerability and apply them promptly once available. 6. Conduct security awareness training for users to recognize suspicious behaviors and avoid interacting with potentially malicious content. 7. Consider deploying Web Application Firewalls (WAFs) with rules tailored to detect and block XSS payloads targeting the Custom Menu. 8. Review and sanitize any stored content in the Custom Menu database to remove potentially malicious scripts already present. 9. Perform regular security assessments and penetration testing focusing on input handling and output rendering in the affected product.