CVE-2025-64059 in Grav
Summary
by MITRE • 09/13/2026
Grav 1.7.50.2 allows admins to enter JavaScript via the Home Page editor. NOTE: the relevance of this for stored XSS is disputed because admins are allowed to modify templates, install plugins, and upload other executable content.
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Analysis
by VulDB Data Team • 09/13/2026
The vulnerability identified in Grav version 1.7.50.2 represents a classic case of Cross-Site Scripting (XSS) within the administrative interface, specifically targeting the Home Page editor functionality. This flaw allows authenticated administrators to inject arbitrary JavaScript code into the content rendered on the home page. While the technical mechanism involves insufficient sanitization or encoding of user-supplied input before it is processed and displayed by the web application, the practical security implications are nuanced due to the privilege level required for exploitation. The core issue lies in the failure to properly escape special characters that have meaning in HTML contexts, such as angle brackets and quotation marks, when these inputs are embedded into dynamic page structures without adequate validation against a strict allowlist of safe content types.
From a technical perspective, this vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. The attack vector requires the attacker to possess administrative credentials or otherwise gain control over an admin account, thereby leveraging existing high-level privileges rather than exploiting a remote unauthenticated entry point. When an administrator inputs JavaScript via the Home Page editor, this script is stored within the system's content repository and subsequently executed in the context of any user who views that specific page. This execution occurs within the browser environment of the victim, granting the injected script full access to the Document Object Model (DOM), cookies, session tokens, and other sensitive data associated with the Grav installation.
The operational impact of this vulnerability is heavily contextualized by the existing permissions granted to administrators in the Grav platform. As noted in the advisory, there is a dispute regarding the severity because administrators already possess extensive capabilities that inherently carry significant risk. Admin users are typically allowed to modify system templates, install and configure plugins, upload executable content such as PHP scripts or binaries, and alter core configuration files. Consequently, an attacker who has compromised administrative credentials can achieve arbitrary code execution through these other means without needing to exploit the specific XSS flaw in the Home Page editor. The stored nature of this XSS means that if a victim with lower privileges views the admin-modified home page, they may inadvertently execute malicious scripts, but since only admins can create such pages, the attack chain is limited to scenarios where an attacker has already breached administrative access or where social engineering targets other users into viewing compromised content.
In terms of threat modeling and industry frameworks, this vulnerability maps to MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter sub-techniques involving JavaScript (T1059.007). The stored aspect corresponds to persistence mechanisms where malicious code is embedded in a persistent location for later execution. However, the relevance of classifying this strictly as a high-severity vulnerability diminishes when considering that the prerequisite condition—administrative access—is itself a critical compromise indicator. In many security assessments, vulnerabilities requiring authentication are often rated lower than unauthenticated remote code executions unless they bypass additional layers of defense or affect non-admin users in a way that leads to privilege escalation. Here, since admins can already execute arbitrary commands via plugins and templates, the XSS vector offers no new capability but rather an alternative method for achieving similar outcomes if other vectors are restricted by specific security policies.
Mitigation strategies should focus on both immediate remediation and long-term defense-in-depth practices. The primary solution is to upgrade Grav to a version where this input validation issue has been addressed through proper output encoding or strict content filtering that strips out script tags and event handlers from the Home Page editor inputs. Administrators must ensure they are running patched versions of all plugins, as third-party extensions may introduce similar vulnerabilities if they do not follow secure coding standards. Furthermore, implementing a Content Security Policy (CSP) header can significantly mitigate the impact of any successful XSS attempt by restricting the sources from which scripts can be loaded and executed, thereby preventing inline script execution even if an attacker manages to inject malicious code. Regular security audits and penetration testing should also include reviews of administrative interfaces to ensure that input validation is robust across all editable fields, not just those explicitly flagged as vulnerable in past advisories.