CVE-2025-53837 in Rendering
Summary
by MITRE • 09/18/2026
XWiki Rendering is a generic rendering system that converts textual input in a given syntax (wiki syntax, HTML, etc) into another syntax (XHTML, etc). Prior to versions 14.10.2 and 15.0 RC1, any user who can edit their own user profile or any other document can execute arbitrary script macros including Groovy and Python macros that allow remote code execution including unrestricted read and write access to all wiki contents. The reason is that rendering output is included as content of HTML macros without further escaping and it is thus possible to close the HTML macro and inject script macros that are executed with programming rights. This has been patched in XWiki 14.10.2 and 15.0 RC1 by making sure that rendering output cannot close the surrounding HTML macro. A possible workaround is available. It is, in principle, possible to add escaping to all places where rendering output is used in wiki documents, but at the moment there is no list of them.
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability identified involves a critical flaw within XWiki's generic rendering system, which serves as the core mechanism for converting textual input from various syntaxes such as wiki markup or HTML into structured outputs like XHTML. This architecture allows users to embed dynamic content and macros that are executed with elevated privileges depending on their context. Prior to versions 14.10.2 and 15.0 RC1, a significant security weakness existed in how rendering output was handled when embedded within HTML macro containers. The system failed to properly escape the rendered output before inserting it into these containers, creating an opportunity for injection attacks that bypass intended access controls.
The technical root cause of this vulnerability lies in the lack of proper escaping mechanisms for rendering outputs used inside HTML macros. When a user edits their own profile or any other document they have permission to modify, the system processes the input through its rendering engine. Because the resulting output is not sanitized against macro delimiters, an attacker can craft specific inputs that close the surrounding HTML macro tag prematurely. This closure allows for the injection of arbitrary script macros, such as Groovy or Python scripts, which are then executed within the context of the application's programming rights rather than standard user permissions.
This flaw leads to severe operational impacts, primarily enabling Remote Code Execution (RCE) with unrestricted capabilities. An authenticated attacker who can edit any document gains the ability to execute arbitrary code on the server hosting XWiki. This includes the capacity to read and write all wiki contents without restriction, effectively compromising the confidentiality, integrity, and availability of the entire platform. The attack vector is classified under CWE-94 as Improper Control of Generation of Code (Code Injection), specifically leveraging injection techniques within a web application context. From an offensive security perspective, this aligns with MITRE ATT&CK technique T1059 Command and Scripting Interpreter, where adversaries use scripting languages to execute commands on compromised systems.
The vulnerability is particularly dangerous because it does not require administrative privileges or complex exploitation chains; basic editing rights are sufficient for a successful attack. The lack of escaping means that any user with write access can potentially escalate their privileges by injecting malicious scripts into the rendering pipeline. This undermines the fundamental security model of XWiki, which relies on strict separation between content and execution logic to prevent unauthorized actions.
Mitigation strategies focus primarily on upgrading to patched versions where this issue has been resolved. In version 14.10.2 and later releases including 15.0 RC1, developers implemented fixes that ensure rendering output cannot close the surrounding HTML macro tags. This prevents the injection of subsequent script macros by maintaining the integrity of the container structure. For environments unable to upgrade immediately, a theoretical workaround involves manually adding escaping logic to all locations where rendering output is utilized within wiki documents. However, this approach is impractical due to the absence of a comprehensive list of affected code paths and the high risk of introducing new bugs or performance issues through manual intervention. Therefore, applying the official patch remains the recommended course of action for maintaining security posture.