CVE-2021-21079 is a reflected Cross-Site Scripting (XSS) vulnerability identified in Adobe Connect, specifically affecting version 11.0.7 and earlier. Adobe Connect is a widely used web conferencing and collaboration platform that enables organizations to conduct virtual meetings, webinars, and training sessions. The vulnerability arises from insufficient input validation or sanitization of user-supplied data in certain web pages or fields within the Adobe Connect application. An attacker can craft a malicious URL or input containing JavaScript code that, when a victim accesses the vulnerable page, is reflected back and executed in the victim's browser context. This reflected XSS attack allows the attacker to execute arbitrary scripts, potentially leading to session hijacking, credential theft, redirection to malicious sites, or unauthorized actions performed on behalf of the victim within the Adobe Connect environment. Since the vulnerability is reflected, it requires the victim to interact with a specially crafted link or input, typically delivered via phishing or social engineering. There are no known public exploits in the wild, and Adobe has not provided official patches linked in the provided data, though updates beyond 11.0.7 may address this issue. The vulnerability is classified under CWE-79, indicating a classic reflected XSS flaw. The attack does not require authentication but does require user interaction to trigger the malicious payload. The vulnerability affects confidentiality and integrity primarily by enabling theft of session tokens or credentials and manipulation of user sessions, but it does not directly impact availability of the Adobe Connect service.

For European organizations, the impact of CVE-2021-21079 can be significant, especially for entities relying heavily on Adobe Connect for remote collaboration, training, and communication. Exploitation could lead to unauthorized access to sensitive meeting content, intellectual property leakage, and compromise of user credentials. This is particularly critical for sectors such as finance, healthcare, government, and education, where confidential information is frequently exchanged. The ability to execute arbitrary scripts in users' browsers can facilitate further attacks such as phishing, malware delivery, or lateral movement within the corporate network. Given the widespread adoption of Adobe Connect in Europe, especially in large enterprises and public sector institutions, the vulnerability could be leveraged to target high-value individuals or groups. However, the requirement for user interaction and the absence of known active exploits somewhat limit immediate widespread impact. Still, the risk remains elevated due to the potential for social engineering campaigns exploiting this vulnerability.

To mitigate CVE-2021-21079 effectively, European organizations should: 1) Upgrade Adobe Connect to the latest available version beyond 11.0.7 where this vulnerability is addressed, or apply any vendor-provided patches as soon as they become available. 2) Implement strict Content Security Policy (CSP) headers on Adobe Connect web servers to restrict execution of unauthorized scripts and reduce the impact of XSS attacks. 3) Employ web application firewalls (WAFs) with rules specifically designed to detect and block reflected XSS payloads targeting Adobe Connect endpoints. 4) Conduct user awareness training focused on recognizing phishing attempts and suspicious links, as exploitation requires user interaction. 5) Monitor logs and network traffic for unusual patterns indicative of attempted XSS exploitation or anomalous user behavior. 6) If upgrading is not immediately feasible, consider temporarily restricting access to Adobe Connect from untrusted networks or implementing additional authentication layers such as multi-factor authentication (MFA) to reduce risk from compromised credentials. 7) Review and sanitize all user inputs and URL parameters in custom Adobe Connect integrations or extensions to prevent injection of malicious scripts.