Executive Summary

CVE-2026-5254 is a stored Cross-Site Scripting (XSS) vulnerability affecting FFmate software versions up to 2.0.15. It exists in the webhook execution response display functionality, specifically in the file /ui/app/components/AppJsonTreeView.vue.

The vulnerability arises because webhook responses are rendered using Vue.js's v-html directive without proper sanitization or validation. This allows malicious JavaScript payloads embedded in webhook responses to execute in the browsers of users viewing those responses.

An attacker can exploit this by configuring webhooks to point to malicious endpoints that return JavaScript payloads. When these responses are displayed in the FFmate UI, the injected scripts execute, potentially compromising user security.

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Impact Analysis

This vulnerability can lead to several security impacts including session hijacking, credential theft, and unauthorized actions performed on behalf of the victim.

Since malicious scripts can execute in the context of the user's browser, attackers may steal sensitive information or manipulate the application to perform actions without the user's consent.

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Detection Guidance

This vulnerability can be detected by testing the webhook execution response display functionality in FFmate versions up to 2.0.15. Specifically, you can create webhooks that point to endpoints returning JavaScript payloads and observe if these scripts execute when viewing webhook execution results in the FFmate UI.

A proof of concept involves running a simple server with endpoints that return malicious payloads, then configuring FFmate webhooks to call these endpoints and checking if the payload executes in the browser.

While no specific commands are provided, you can use tools like curl or wget to simulate webhook calls and inspect responses, for example:

• curl -v http://your-webhook-endpoint/xss
• Observe the FFmate UI webhook execution results for script execution.

Additionally, monitoring network traffic for suspicious webhook responses containing script tags or JavaScript payloads can help detect exploitation attempts.

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Mitigation Strategies

Immediate mitigation steps include:

• Avoid using the vulnerable FFmate versions (up to 2.0.15) or upgrade to a version where this vulnerability is fixed.
• Implement HTML sanitization on webhook response content before rendering, using libraries such as DOMPurify.
• Avoid using Vue.js's `v-html` directive to render raw HTML from webhook responses; instead, use safer rendering methods that do not execute scripts.
• Apply Content Security Policy (CSP) headers to restrict script execution in the FFmate UI.
• Validate and whitelist allowed HTML tags and attributes in webhook responses.

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Compliance Impact

The vulnerability is a stored Cross-Site Scripting (XSS) issue that allows attackers to execute arbitrary JavaScript in the browsers of users viewing webhook execution results. This can lead to session hijacking, credential theft, or unauthorized actions performed on behalf of the victim.

Such security risks can impact compliance with common standards and regulations like GDPR and HIPAA, which require protection of personal data and secure handling of user credentials and sessions. Exploitation of this vulnerability could lead to unauthorized access to sensitive information or user accounts, potentially resulting in data breaches and non-compliance with these regulations.

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