CVE-2024-23191 is a cross-site scripting vulnerability identified in the Open-Xchange GmbH OX App Suite, a widely used collaboration and communication platform. The vulnerability stems from improper neutralization of input during web page generation, specifically in the upsell advertisement content associated with user accounts. An attacker can manipulate this upsell content to inject malicious script code that executes within the victim's browser session context. Exploitation requires the attacker to have temporary access to the victim's account or to successfully conduct social engineering attacks that trick users into interacting with maliciously configured accounts. Once exploited, the attacker can perform unauthorized API requests on behalf of the user or extract sensitive information from the user's account, compromising confidentiality and integrity. The vulnerability does not affect system availability. The vendor has addressed the issue by improving sanitization of user-defined upsell content and has released patches. The CVSS v3.1 score is 5.4 (medium severity), reflecting network attack vector, low complexity, requiring privileges and user interaction, with a scope change and partial impact on confidentiality and integrity. No known public exploits exist, but the risk remains significant due to the potential for targeted social engineering and account compromise.

For European organizations, this vulnerability poses a risk to the confidentiality and integrity of user data within OX App Suite environments. Attackers exploiting this flaw could access sensitive corporate communications, perform unauthorized actions via API calls, or exfiltrate information, potentially leading to data breaches or lateral movement within networks. Given that OX App Suite is used by various enterprises and service providers across Europe, especially in Germany and neighboring countries where Open-Xchange GmbH is headquartered, the impact could be substantial. The requirement for temporary account access or social engineering reduces the likelihood of widespread automated exploitation but increases the risk of targeted attacks against high-value users or organizations. This could affect sectors with sensitive data such as finance, healthcare, and government agencies. Additionally, the vulnerability could undermine trust in collaboration platforms and lead to compliance issues under GDPR if personal data is compromised.

European organizations should immediately deploy the vendor-provided patches and updates to OX App Suite to remediate the vulnerability. Beyond patching, organizations should implement strict access controls and monitoring to detect unusual account activities that might indicate temporary account compromise. User education campaigns should be conducted to raise awareness about social engineering tactics, emphasizing caution when interacting with unexpected upsell content or unfamiliar accounts. Employing multi-factor authentication (MFA) can reduce the risk of account takeover. Network-level protections such as web application firewalls (WAFs) can be tuned to detect and block suspicious script injections or API misuse. Regular security assessments and penetration testing of the OX App Suite deployment can help identify residual risks. Finally, organizations should establish incident response plans specific to web application attacks and data exfiltration scenarios to minimize damage if exploitation occurs.