CVE-2025-59025 is a cross-site scripting (XSS) vulnerability identified in the Open-Xchange GmbH OX App Suite, a widely used web-based collaboration and email platform. The vulnerability arises from improper neutralization of input during web page generation, specifically when rendering email content. Malicious actors can craft email messages containing embedded script code that, when viewed by a user, executes within the security context of the user's session. This can lead to unauthorized actions such as exfiltration of sensitive information, session hijacking, or manipulation of user data. The vulnerability requires user interaction, typically opening or previewing a malicious email, and does not require prior authentication, increasing its risk profile. The CVSS v3.1 score of 6.1 reflects a medium severity, with network attack vector, low attack complexity, no privileges required, but user interaction necessary, and a scope change indicating that the vulnerability can affect components beyond the initially vulnerable module. The vendor has updated input sanitization routines to prevent bypasses that allowed script injection. No public exploits are currently known, but the potential for targeted phishing campaigns exploiting this vulnerability exists. The vulnerability was reserved in September 2025 and published in November 2025, indicating recent discovery and disclosure.

For European organizations, the impact of CVE-2025-59025 can be significant, especially for those relying on OX App Suite for email and collaboration. Successful exploitation could lead to unauthorized access to sensitive corporate or personal information, including emails, contacts, and calendar data. This can result in data breaches, loss of confidentiality, and potential compliance violations under regulations such as GDPR. Additionally, attackers could perform actions on behalf of the user, potentially leading to further compromise or lateral movement within networks. The medium severity and requirement for user interaction suggest that phishing or social engineering campaigns could be effective attack vectors. Organizations in sectors with high confidentiality requirements, such as government, finance, and healthcare, are particularly at risk. The lack of known public exploits reduces immediate widespread threat but does not eliminate the risk of targeted attacks.

To mitigate CVE-2025-59025, European organizations should immediately apply any patches or updates released by Open-Xchange GmbH that address input sanitization flaws. In the absence of patches, organizations should consider implementing web application firewalls (WAFs) with rules to detect and block malicious script payloads in email content. Enhancing email security gateways to filter and quarantine suspicious emails can reduce exposure. User awareness training focused on recognizing phishing attempts and avoiding interaction with suspicious emails is critical. Organizations should also review and harden browser security settings and consider disabling automatic email content rendering features that could trigger script execution. Regular security assessments and monitoring for anomalous user activity can help detect exploitation attempts early. Finally, maintaining an incident response plan tailored to web application and email-based attacks will improve readiness.