CVE-2025-66094 identifies a Stored Cross-Site Scripting (XSS) vulnerability in the Yada Wiki software developed by dmccan, affecting versions up to 3.5. The vulnerability stems from improper neutralization of user-supplied input during web page generation, classified under CWE-79. Stored XSS means that malicious scripts injected by an attacker are saved on the server and executed in the browsers of users who view the affected pages. The CVSS 3.1 vector indicates the attack can be performed remotely over the network (AV:N) with low attack complexity (AC:L), but requires privileges (PR:L) and user interaction (UI:R). The scope is changed (S:C), meaning the vulnerability can affect components beyond the initially vulnerable one. The impact includes partial loss of confidentiality, integrity, and availability (C:L/I:L/A:L), as attackers can execute arbitrary JavaScript to steal session tokens, manipulate content, or cause denial of service. No patches or known exploits are currently available, but the vulnerability is publicly disclosed and should be addressed promptly. The lack of patch links suggests that users must implement interim mitigations. The vulnerability is particularly relevant for organizations using Yada Wiki for collaborative documentation or knowledge management, where multiple users access and contribute content. Stored XSS vulnerabilities are dangerous because they can propagate widely and persist until remediated. The vulnerability was reserved in November 2025 and published in December 2025, indicating recent discovery. The technical details confirm the vulnerability’s classification and severity, emphasizing the need for input validation and output encoding in the application’s codebase to prevent injection of malicious scripts.

For European organizations, the impact of CVE-2025-66094 can be significant, especially for those relying on Yada Wiki for internal or external collaboration, documentation, or knowledge sharing. Exploitation could allow attackers to execute arbitrary scripts in the context of authenticated users, potentially leading to session hijacking, unauthorized actions, data theft, or defacement. This can undermine trust, cause data breaches, and disrupt operations. Public sector entities, academic institutions, and enterprises using Yada Wiki may face reputational damage and compliance issues under GDPR if personal data is exposed. The medium severity rating reflects that while exploitation requires some privileges and user interaction, the vulnerability affects confidentiality, integrity, and availability. The stored nature means the malicious payload can affect multiple users over time, increasing the risk. Without patches, organizations may need to rely on compensating controls, increasing operational overhead. The threat is heightened in environments with high user turnover or public-facing wiki pages, where attackers can reach a broader audience. Overall, the vulnerability poses a moderate but tangible risk to European organizations using the affected software.

To mitigate CVE-2025-66094 effectively, European organizations should: 1) Immediately audit and restrict user privileges in Yada Wiki to minimize the ability of low-privilege users to inject content. 2) Implement strict input validation and sanitization on all user-supplied data before storing or rendering it, using well-maintained libraries designed to prevent XSS. 3) Apply context-aware output encoding on all dynamic content rendered in the wiki pages to neutralize any injected scripts. 4) Employ Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers accessing the wiki. 5) Monitor logs and user activity for unusual content submissions or script injections. 6) Educate users about the risks of interacting with untrusted content and encourage cautious behavior. 7) Isolate the wiki environment from critical systems to limit potential lateral movement in case of compromise. 8) Stay alert for official patches or updates from dmccan and apply them promptly once available. 9) Consider deploying web application firewalls (WAFs) with custom rules to detect and block XSS payloads targeting Yada Wiki. 10) Regularly review and update security policies governing collaborative platforms to incorporate lessons learned from this vulnerability.