CVE-2025-30931 is a medium-severity Stored Cross-Site Scripting (XSS) vulnerability classified under CWE-79, affecting the product «Подсказки» от DaData.ru developed by Shamil Shafeev. This vulnerability arises due to improper neutralization of input during web page generation, allowing malicious actors to inject and store malicious scripts within the application. When other users access the affected pages, the malicious scripts execute in their browsers, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of the user. The vulnerability affects versions up to 1.0.6, with no specific version range detailed beyond 'n/a through 1.0.6'. The CVSS v3.1 base score is 5.9, indicating a medium severity level, with the vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L. This means 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), indicating the vulnerability affects resources beyond the initially vulnerable component. The impact on confidentiality, integrity, and availability is low to moderate. No known exploits are currently reported in the wild, and no patches or mitigations have been linked yet. The vulnerability was reserved in March 2025 and published in June 2025. Stored XSS vulnerabilities are particularly dangerous because they can persist on the server and affect multiple users over time, increasing the attack surface and potential damage. The product «Подсказки» от DaData.ru is a tool/service presumably used for data suggestions or autocomplete, likely integrated into web applications, which may increase exposure if widely deployed.

For European organizations using «Подсказки» от DaData.ru, this vulnerability poses a risk of client-side attacks that could compromise user sessions, leak sensitive information, or perform unauthorized actions within the context of the affected web applications. Given the stored nature of the XSS, attackers could embed malicious scripts that persist and affect multiple users, potentially leading to widespread compromise of user accounts or data integrity. This is particularly concerning for organizations handling sensitive personal data or financial information, as exploitation could facilitate phishing, fraud, or data breaches. The requirement for high privileges to exploit somewhat limits the attacker's capabilities but does not eliminate risk, especially if internal users or administrators are targeted. The need for user interaction means social engineering or phishing could be used to trigger the exploit. The scope change indicates that the vulnerability could impact other components or domains, increasing potential damage. Overall, the vulnerability could undermine trust in affected services, cause regulatory compliance issues under GDPR due to data leakage, and disrupt business operations if exploited at scale.

Specific mitigation steps include: 1) Immediate code review and implementation of proper input validation and output encoding to neutralize malicious scripts before storage and rendering. Use established libraries or frameworks that automatically handle XSS protection. 2) Implement Content Security Policy (CSP) headers to restrict the execution of unauthorized scripts in browsers. 3) Conduct thorough security testing, including automated and manual penetration testing focused on stored XSS vectors within the application. 4) Limit privileges of users who can input data that is rendered to others, reducing the risk of high-privilege exploitation. 5) Educate users and administrators about the risks of social engineering and encourage cautious interaction with suspicious content. 6) Monitor logs and user activity for unusual behavior that may indicate exploitation attempts. 7) If possible, isolate or sandbox components that handle user-generated content to contain potential attacks. 8) Coordinate with DaData.ru or the vendor for official patches or updates and apply them promptly once available.