CVE-2025-45055 is a stored cross-site scripting (XSS) vulnerability identified in Silverpeas version 6.4.2, specifically within its event management module. The vulnerability allows an authenticated user to upload a malicious SVG (Scalable Vector Graphics) file as an event attachment. Due to insufficient sanitization of SVG content, embedded JavaScript within the SVG file is not properly neutralized. When an administrator views the event attachment, the malicious script executes in the context of the administrator's session. This script execution can be leveraged by attackers to escalate privileges, notably by creating a new administrator account within the Silverpeas platform. The vulnerability is further exacerbated by weak Cross-Site Request Forgery (CSRF) protections, which may allow attackers to perform unauthorized actions on behalf of the administrator once the malicious script is executed. The CVSS v3.1 base score is 5.4 (medium severity), reflecting that the attack vector is network-based, requires low attack complexity, but does require privileges (authenticated user) and user interaction (administrator viewing the malicious attachment). The vulnerability impacts confidentiality and integrity by enabling unauthorized privilege escalation but does not affect availability. No known exploits in the wild have been reported yet, and no patches are currently linked, indicating that organizations using Silverpeas 6.4.2 should prioritize mitigation efforts to prevent exploitation.

For European organizations using Silverpeas 6.4.2, this vulnerability poses a significant risk to internal security and administrative control. Since the attack requires an authenticated user to upload a malicious SVG file, insider threats or compromised user accounts could be leveraged to exploit this vulnerability. Successful exploitation allows attackers to escalate privileges to administrator level, potentially leading to unauthorized access to sensitive data, manipulation of event information, and broader compromise of the Silverpeas environment. This could result in data breaches, loss of data integrity, and undermining of trust in internal collaboration platforms. Given that Silverpeas is a collaborative platform often used in enterprise and government environments, the impact on confidentiality and integrity is critical. European organizations with strict data protection regulations such as GDPR could face compliance issues and legal consequences if such a breach occurs. Additionally, weak CSRF protections increase the risk of automated or remote exploitation once the malicious SVG is viewed by an administrator, amplifying the threat. The lack of availability impact means systems remain operational, but the stealthy nature of privilege escalation could allow prolonged undetected access.

To mitigate this vulnerability, European organizations should implement the following specific measures: 1) Immediately restrict the ability to upload SVG files or any vector graphics as event attachments until a patch is available. 2) Enforce strict input validation and sanitization on all uploaded SVG files, ideally by disabling script execution within SVG content or converting SVGs to safer formats before rendering. 3) Enhance CSRF protections by implementing robust anti-CSRF tokens and verifying the origin of requests, especially for administrative actions. 4) Limit event attachment upload permissions to the minimum necessary user roles and monitor upload activities for suspicious behavior. 5) Educate administrators to be cautious when viewing event attachments and to report any unusual behavior. 6) Implement strong authentication and session management controls to reduce the risk of compromised user accounts. 7) Monitor logs for unusual administrative account creation or privilege changes. 8) Prepare for rapid patch deployment once an official fix is released by Silverpeas or the community. These targeted actions go beyond generic advice by focusing on the specific attack vector (SVG uploads) and the privilege escalation mechanism.