Overview
This blog post examines the critical vulnerability, CVE-2025-53836, identified in XWiki Rendering, a generic system used for converting various syntaxes. This vulnerability poses a serious threat due to its severity and potential impact, which includes system compromise and data leakage. It affects XWiki versions starting from 4.2-milestone-1 and prior to versions 13.10.11, 14.4.7, and 14.10. As such, any organization or user employing these versions of XWiki is at risk and should take immediate actions to mitigate this vulnerability.
Vulnerability Summary
CVE ID: CVE-2025-53836
Severity: Critical (CVSS: 9.9)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: Potential system compromise or data leakage
Affected Products
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Product | Affected Versions
XWiki | 4.2-milestone-1 to 13.10.10
XWiki | 4.2-milestone-1 to 14.4.6
XWiki | 4.2-milestone-1 to 14.9
How the Exploit Works
The vulnerability lies in the default macro content parser of XWiki Rendering system. When executing nested macros, it fails to preserve the restricted attribute of the transformation context. This lapse allows the execution of macros that are typically forbidden in restricted mode, including script macros. Particularly, the cache and chart macros that are bundled in XWiki can exploit this vulnerability. This flaw in the parser creates a potential pathway for unauthorized code execution, leading to system compromise or data leakage.
Conceptual Example Code
The following conceptual example provides an insight into how the vulnerability might be exploited. This could be a possible HTTP request exploiting the vulnerability:
POST /XWiki/RenderMacro HTTP/1.1
Host: target.example.com
Content-Type: application/x-www-form-urlencoded
macro_name=script¯o_content=<script>malicious_code_here</script>In the above example, an attacker could potentially embed malicious code within the script macro, which gets executed due to the parser’s inability to enforce restrictions.
Mitigation Guidance
Users are urged to apply the patch provided by the vendor for XWiki versions 13.10.11, 14.4.7 and 14.10. As an interim mitigation measure, users could use a Web Application Firewall (WAF) or Intrusion Detection System (IDS) to monitor and block malicious traffic. Furthermore, to avoid the exploitation of this bug, it is recommended to disable comments for untrusted users until the system is upgraded to a patched version. It is important to note that users with edit rights will still be able to add comments via the object editor even if comments have been disabled.