CVE-2026-85613 in OpenPanel
Summary
by MITRE • 09/04/2026
OpenPanel before 2.3.0 contains a cross-site scripting vulnerability in the unauthenticated favicon proxy endpoint GET /misc/favicon that allows remote attackers to execute scripts by supplying an SVG file URL. Attackers can host malicious SVG files with embedded scripts that execute in the victim's browser on the API origin, enabling same-origin credentialed requests to authenticated endpoints.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in OpenPanel versions prior to 2.3.0 represents a significant security flaw within its unauthenticated favicon proxy endpoint located at GET /misc/favicon. This component is designed to fetch and serve icon images for websites, but it fails to properly sanitize or validate the input provided by remote attackers. Specifically, when an attacker supplies a URL pointing to an SVG file hosted on a malicious server, OpenPanel retrieves this external resource without adequate security checks regarding its content type or structure. The core technical flaw lies in the application's handling of XML-based vector graphics files, which can contain executable JavaScript code within their markup. By leveraging this lack of input validation, remote attackers are able to inject arbitrary scripts that execute directly within the context of the victim's browser session on the OpenPanel origin domain.
This cross-site scripting vulnerability is particularly dangerous because it operates in an unauthenticated state, meaning no prior access credentials are required to trigger the exploit. Once a user with administrative or elevated privileges visits a page containing the malicious payload, the embedded JavaScript executes immediately. Because the script runs within the same-origin context of the OpenPanel application, it inherits all associated cookies and session tokens. This capability allows attackers to perform authenticated actions on behalf of the victim without their knowledge or consent. The attacker can manipulate the DOM, steal sensitive data such as administrative credentials or configuration files, or even modify system settings by sending credentialed requests to other endpoints within the OpenPanel API that rely on standard browser-based authentication mechanisms.
From a classification perspective, this vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting (XSS). The specific mechanism involves reflected or stored script injection via an image proxy service, exploiting the trust relationship between the browser and the application domain. In terms of offensive security frameworks, this attack vector maps to MITRE ATT&CK technique T1059, specifically sub-technique 007 for JavaScript execution. It also relates to T1204, User Execution, as it requires a user interaction such as visiting a compromised page or clicking a link containing the malicious SVG URL. The ability to execute scripts in the context of an authenticated session further escalates the risk profile by enabling lateral movement and privilege escalation within the web application environment.
The operational impact of this vulnerability is severe, potentially leading to complete compromise of the OpenPanel instance if accessed by high-privilege users. Attackers can exfiltrate sensitive information including database credentials, API keys, or user session data stored in local storage or cookies. Furthermore, they could deface the application interface, redirect traffic to phishing sites, or use the compromised server as a pivot point for further network attacks against internal systems that trust the OpenPanel domain. The lack of authentication requirement makes this vulnerability highly exploitable at scale, allowing attackers to target any user who interacts with maliciously crafted links while logged into their OpenPanel account.
To mitigate this risk, organizations running versions of OpenPanel prior to 2.3.0 should immediately upgrade to version 2.3.0 or later where the issue has been addressed through improved input validation and output encoding mechanisms for the favicon proxy endpoint. If upgrading is not immediately feasible, administrators can implement a Web Application Firewall rule to block requests containing SVG file extensions in the URL parameters of the /misc/favicon path. Additionally, enforcing strict Content Security Policy headers that restrict script execution from external domains or disable inline scripts can significantly reduce the impact of successful XSS attempts. Regular security audits and penetration testing focusing on input validation across all proxy endpoints are recommended to prevent similar vulnerabilities in other components of the application infrastructure.