CVE-2021-21080 is a reflected Cross-Site Scripting (XSS) vulnerability identified in Adobe Connect, specifically affecting version 11.0.7 and earlier. Reflected XSS vulnerabilities occur when untrusted user input is immediately returned by a web application without proper sanitization or encoding, allowing an attacker to inject malicious JavaScript code. In this case, the vulnerability allows an attacker to craft a specially crafted URL or input that, when visited or processed by a victim's browser, executes arbitrary JavaScript within the security context of the Adobe Connect web application. This can lead to session hijacking, credential theft, or unauthorized actions performed on behalf of the victim. Adobe Connect is a widely used web conferencing and collaboration platform, often deployed in enterprise and educational environments. The vulnerability does not require authentication to exploit, as it is reflected and triggered by victim interaction with a malicious link or page. No known public exploits have been reported in the wild as of the published date. The vulnerability is classified under CWE-79, which covers improper neutralization of input leading to XSS. The lack of a patch link suggests that remediation may require updating to a newer version or applying vendor-recommended mitigations. Given the nature of reflected XSS, the attack vector relies on social engineering to lure users into clicking malicious links or visiting compromised pages hosting the payload. The vulnerability impacts the confidentiality and integrity of user sessions and data within Adobe Connect, but does not directly affect system availability.

For European organizations, the impact of this vulnerability can be significant, especially for those relying heavily on Adobe Connect for remote collaboration, training, and communication. Successful exploitation can lead to theft of session cookies or credentials, enabling attackers to impersonate legitimate users and gain unauthorized access to sensitive meetings, documents, or internal communications. This can result in data breaches, intellectual property theft, or disruption of business operations. Educational institutions and government agencies using Adobe Connect are particularly at risk due to the sensitive nature of their data and regulatory compliance requirements such as GDPR. Additionally, the vulnerability could be leveraged as a foothold for further attacks within the network if attackers gain access to privileged accounts. Although the vulnerability does not directly impact system availability, the reputational damage and potential regulatory penalties from data exposure could be severe. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, as attackers may develop exploits or use social engineering tactics to target users.

European organizations should prioritize upgrading Adobe Connect to the latest version where this vulnerability is patched. If immediate upgrading is not feasible, organizations should implement strict input validation and output encoding on all user-supplied data fields within Adobe Connect interfaces to prevent script injection. Deploying Web Application Firewalls (WAFs) with rules specifically designed to detect and block reflected XSS payloads targeting Adobe Connect can provide an additional layer of defense. User awareness training is critical to reduce the risk of social engineering attacks that rely on malicious links; users should be educated to verify URLs and avoid clicking suspicious links related to Adobe Connect sessions. Organizations should also monitor logs for unusual activity indicative of session hijacking or unauthorized access attempts. Implementing Content Security Policy (CSP) headers can help mitigate the impact of XSS by restricting the execution of unauthorized scripts. Finally, organizations should review and tighten session management controls, such as enforcing secure cookies and short session lifetimes, to limit the window of opportunity for attackers.