CVE-2022-40879 is a Cross Site Scripting (XSS) vulnerability identified in kkFileView version 4.1.0. The vulnerability arises from improper sanitization of the 'errorMsg' parameter, which allows an attacker to inject malicious scripts into the web application. When a victim user accesses a crafted URL or interacts with the application in a way that triggers the vulnerable parameter, the injected script executes in the context of the victim's browser. This can lead to theft of session cookies, user impersonation, or other malicious actions that compromise the confidentiality and integrity of user data. The vulnerability is classified under CWE-79, which pertains to improper neutralization of input during web page generation. The CVSS v3.1 base score is 6.1, indicating a medium severity level. The vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N indicates that the attack can be launched remotely over the network without privileges, requires low attack complexity, no privileges, but does require user interaction (UI:R). The scope is changed (S:C), meaning the vulnerability affects resources beyond the vulnerable component. The impact affects confidentiality and integrity to a low degree, with no impact on availability. There are no known exploits in the wild and no patches or vendor information provided in the data. The vulnerability was published on September 29, 2022.

For European organizations using kkFileView 4.1.0, this XSS vulnerability poses a risk primarily to web application users. Successful exploitation could allow attackers to hijack user sessions, steal sensitive information, or perform actions on behalf of users, potentially leading to data breaches or unauthorized access to internal resources. Given the nature of kkFileView as a file viewing/sharing platform, compromised sessions could expose confidential documents or internal communications. Although the vulnerability requires user interaction, phishing or social engineering campaigns could be used to lure users into triggering the exploit. The medium severity rating suggests a moderate risk, but the changed scope indicates that the impact could extend beyond the immediate vulnerable component, potentially affecting other integrated systems or services. European organizations with strict data protection regulations such as GDPR must consider the risk of data leakage and reputational damage. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially if attackers develop exploits in the future.

Organizations should prioritize upgrading kkFileView to a version where this vulnerability is patched once available. In the absence of an official patch, immediate mitigations include implementing web application firewall (WAF) rules to detect and block malicious payloads targeting the 'errorMsg' parameter. Input validation and output encoding should be enforced at the application level to sanitize user-supplied data. Security teams should conduct thorough code reviews and penetration testing focused on XSS vectors within kkFileView. User awareness training to recognize phishing attempts can reduce the likelihood of successful exploitation. Additionally, organizations should monitor logs for suspicious activity related to the vulnerable parameter and consider isolating or restricting access to kkFileView instances to trusted networks or VPNs. Employing Content Security Policy (CSP) headers can help mitigate the impact of XSS by restricting script execution contexts.