CVE-2025-65516 is a stored cross-site scripting (XSS) vulnerability identified in Seafile Community Edition prior to version 13.0.12, specifically when the software is configured to use the Golang file server. The vulnerability arises because Seafile allows users to upload SVG files that can contain embedded JavaScript. An attacker can craft a malicious SVG file with embedded JavaScript payload and upload it to the server. By sharing the file through a public link, the attacker can lure victims into opening the link, which causes the embedded JavaScript to execute in the victim's browser context. This execution can lead to various malicious outcomes such as session hijacking, theft of authentication tokens, unauthorized actions on behalf of the user, or delivery of further malware. The vulnerability is classified as stored XSS because the malicious script is stored on the server and served to any user accessing the shared link. The issue was resolved in Seafile Community Edition 13.0.12 by sanitizing SVG uploads or restricting script execution within SVG files. No public exploits have been reported to date, but the vulnerability poses a significant risk due to the ease of exploitation via public file sharing. The lack of a CVSS score suggests this is a newly published vulnerability. The attack vector requires no authentication but does require user interaction (opening the malicious link).

For European organizations, this vulnerability can have serious consequences, especially for those using Seafile Community Edition for file sharing and collaboration. The stored XSS can lead to compromise of user sessions, unauthorized access to sensitive data, and potential lateral movement within the network if attackers leverage stolen credentials or tokens. Organizations that enable public sharing of files are particularly vulnerable, as attackers can distribute malicious SVG files widely. This can impact confidentiality and integrity of data, and potentially availability if attackers use the vulnerability to deploy further attacks or disrupt services. Given the collaborative nature of Seafile, attacks could propagate quickly among users. The impact is heightened in sectors with strict data protection regulations such as GDPR, where data breaches can lead to significant fines and reputational damage. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, as attackers may develop exploits rapidly once the vulnerability is public.

European organizations should immediately upgrade Seafile Community Edition to version 13.0.12 or later to apply the official fix. Until the update is applied, organizations should disable public sharing of SVG files or restrict SVG uploads entirely to prevent malicious file uploads. Implement content security policies (CSP) in browsers to restrict script execution from untrusted sources. Conduct user awareness training to caution users against opening suspicious or unexpected public links. Monitor file uploads and shared links for unusual activity or files with embedded scripts. Employ web application firewalls (WAF) with rules to detect and block malicious SVG payloads. Regularly audit Seafile configurations to ensure secure settings are enforced, and maintain up-to-date backups to recover from potential attacks. Finally, integrate vulnerability scanning into the software update lifecycle to detect similar issues proactively.