CVE-2017-16807 in Kirby Panel
Summary
by MITRE
A cross-site Scripting (XSS) vulnerability in Kirby Panel before 2.3.3, 2.4.x before 2.4.2, and 2.5.x before 2.5.7 exists when displaying a specially prepared SVG document that has been uploaded as a content file.
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Analysis
by VulDB Data Team • 09/07/2025
This cross-site scripting vulnerability affects the Kirby CMS panel and represents a critical security flaw that enables attackers to execute malicious scripts in the context of authenticated users. The vulnerability specifically targets versions prior to 2.3.3, 2.4.2, and 2.5.7, creating a window of opportunity for exploitation across multiple release branches. The flaw manifests when the panel processes SVG files that contain malicious payloads, allowing attackers to inject arbitrary JavaScript code that executes in the victim's browser session.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the Kirby Panel's content handling mechanisms. When users upload SVG files containing specially crafted malicious code, the system fails to properly sanitize the file contents before displaying them within the admin interface. This oversight creates a direct path for attackers to inject XSS payloads that can execute in the context of authenticated admin sessions, potentially leading to complete system compromise. The vulnerability operates at the application layer and falls under CWE-79, which specifically addresses cross-site scripting flaws in software applications. The attack vector leverages the trust relationship between the authenticated user and the admin panel, making it particularly dangerous in environments where administrative privileges are held by trusted personnel.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform a wide range of malicious activities within the compromised system. An attacker with access to the panel could manipulate content, steal session cookies, redirect users to malicious sites, or even escalate privileges to gain full administrative control over the CMS. The vulnerability is particularly concerning because it requires minimal user interaction beyond uploading a malicious file, making it an attractive target for automated exploitation. This weakness directly aligns with ATT&CK technique T1059.007, which covers script execution through web shells, and represents a common vector for privilege escalation attacks in content management systems. The compromised session could allow attackers to modify website content, delete files, or establish persistent access through backdoor installations.
Mitigation strategies should focus on immediate version upgrades to patched releases, specifically targeting versions 2.3.3, 2.4.2, and 2.5.7 or later. Organizations should implement strict file validation policies that prevent SVG uploads or enforce comprehensive sanitization of all uploaded content files. The recommended approach includes implementing Content Security Policy headers to limit script execution, deploying web application firewalls to detect and block malicious payloads, and establishing regular security audits of uploaded content. Additionally, administrators should consider implementing multi-factor authentication for admin accounts and monitoring for suspicious upload activities. Security teams should also review their incident response procedures to ensure rapid detection and remediation of similar vulnerabilities in other CMS components. The vulnerability highlights the importance of comprehensive input validation and output encoding practices in web applications, particularly when handling user-uploaded content that may contain executable code or markup languages like SVG that can contain scripting elements.