CVE-2025-46558 is a critical cross-site scripting (XSS) vulnerability affecting the xwiki-contrib syntax-markdown component, specifically in versions 8.2 up to but not including 8.9. This component enables importing Markdown content into XWiki pages and creating wiki content using Markdown syntax. The vulnerability arises from improper neutralization of input during web page generation, allowing malicious users to embed arbitrary JavaScript code within Markdown content. When other users, including those with administrative or programming rights, view the affected wiki pages or comments, the embedded script executes in their browsers. This can lead to a full compromise of the XWiki installation’s confidentiality, integrity, and availability. The vulnerability is exploitable remotely over the network without complex attack conditions, requiring only limited privileges (authenticated user) and user interaction (viewing the malicious content). The scope is significant because the vulnerability affects all users who access the compromised content, and if administrators are impacted, the attacker can gain control over the entire wiki environment. The issue was patched in version 8.9 of syntax-markdown, and no known exploits are reported in the wild as of the publication date. The CVSS v3.1 base score is 9.1, reflecting the critical nature of this vulnerability with high impact on confidentiality, integrity, and availability, low attack complexity, and the requirement of limited privileges and user interaction.

For European organizations using XWiki with the vulnerable syntax-markdown versions, this vulnerability poses a severe risk. XWiki is often used for internal collaboration, documentation, and knowledge management, which may contain sensitive corporate or personal data. Exploitation could lead to unauthorized disclosure of confidential information, unauthorized modification or deletion of wiki content, and disruption of wiki services. If attackers execute scripts in the context of users with elevated privileges, they could escalate their access, implant persistent backdoors, or manipulate critical organizational data. This could impact business continuity, regulatory compliance (e.g., GDPR), and damage organizational reputation. The collaborative nature of wikis increases the risk of propagation, as multiple users interact with the content. Given the criticality and ease of exploitation, organizations relying on vulnerable XWiki versions should prioritize remediation to prevent potential data breaches and operational disruptions.

1. Immediate upgrade of the syntax-markdown component to version 8.9 or later, where the vulnerability is patched. 2. Implement strict input validation and output encoding on Markdown content to prevent script injection, even beyond the patched version, as a defense-in-depth measure. 3. Restrict write permissions to trusted users only, minimizing the risk of malicious content insertion. 4. Enable Content Security Policy (CSP) headers on the XWiki web server to limit the execution of unauthorized scripts. 5. Regularly audit wiki content for suspicious or unexpected scripts or HTML tags, especially in comments and user-generated content. 6. Educate users about the risks of executing untrusted content and encourage reporting of suspicious wiki pages. 7. Monitor logs for unusual activities related to wiki content creation or modification, focusing on users with elevated privileges. 8. If upgrading immediately is not feasible, consider temporarily disabling Markdown content import or restricting it to administrators until the patch can be applied.