CVE-2026-6107: 1Panel-dev MaxKB XSS Vulnerability

CVE-2026-6107 Overview

A Cross-Site Scripting (XSS) vulnerability has been discovered in 1Panel-dev MaxKB, an open-source knowledge base management platform. The flaw exists in the ChatHeadersMiddleware component within the file apps/common/middleware/chat_headers_middleware.py, where improper handling of the Name argument allows attackers to inject malicious scripts. This vulnerability enables remote exploitation, potentially allowing attackers to execute arbitrary JavaScript in the context of victim users' browsers.

Critical Impact

Remote attackers can exploit this XSS vulnerability to inject malicious scripts through application name manipulation, potentially leading to session hijacking, credential theft, or phishing attacks against MaxKB users.

Affected Products

• 1Panel-dev MaxKB versions up to 2.6.1
• MaxKB ChatHeadersMiddleware component
• Applications utilizing apps/common/middleware/chat_headers_middleware.py

Discovery Timeline

• 2026-04-12 - CVE-2026-6107 published to NVD
• 2026-04-13 - Last updated in NVD database

Technical Details for CVE-2026-6107

Vulnerability Analysis

This vulnerability is classified as CWE-79 (Cross-Site Scripting), which occurs when an application includes untrusted data in web output without proper validation or escaping. In the case of MaxKB, the ChatHeadersMiddleware component fails to sanitize the Name argument before processing, allowing attackers to inject malicious payloads that are rendered in users' browsers.

The vulnerability is remotely exploitable over the network and requires low privileges to execute. However, user interaction is required for successful exploitation, as victims must interact with the malicious content. While the integrity impact is limited, this flaw can be leveraged for various attack scenarios including session hijacking, defacement, and credential harvesting.

Root Cause

The root cause of this vulnerability is the absence of proper HTML entity encoding when handling the application name parameter in the ChatHeadersMiddleware. The middleware component directly processes user-controllable input without implementing adequate sanitization measures, allowing XSS payloads to be injected and executed.

Attack Vector

The attack can be performed remotely over the network. An authenticated attacker with low-level privileges can manipulate the Name argument to inject malicious JavaScript code. When other users interact with the affected application component, the injected script executes in their browser context, potentially compromising their session or credentials.

The fix implemented in version 2.8.0 introduces proper HTML escaping using Python's built-in html.escape() function:

 
from common.cache_data.application_access_token_cache import get_application_access_token
from maxkb.const import CONFIG
+from html import escape


class ChatHeadersMiddleware(MiddlewareMixin):

Source: GitHub MaxKB Commit

This patch imports the escape function from the html module to properly sanitize user input before rendering, effectively neutralizing XSS payloads by converting special HTML characters to their entity equivalents.

Detection Methods for CVE-2026-6107

Indicators of Compromise

• Unusual JavaScript execution or unexpected script tags in application name fields
• Web application logs showing encoded script payloads in the Name parameter
• User reports of unexpected browser behavior or pop-ups when accessing MaxKB
• Network traffic containing HTML/JavaScript injection patterns targeting the ChatHeadersMiddleware endpoint

Detection Strategies

• Implement web application firewall (WAF) rules to detect XSS patterns in HTTP requests targeting MaxKB endpoints
• Monitor application logs for suspicious input patterns containing script tags, event handlers, or encoded JavaScript
• Deploy browser-based security controls like Content Security Policy (CSP) to detect and prevent inline script execution
• Use security scanning tools to identify unpatched MaxKB instances in your environment

Monitoring Recommendations

• Enable detailed logging for the ChatHeadersMiddleware component to capture all name parameter inputs
• Set up alerts for requests containing common XSS payload signatures such as <script>, javascript:, or event handlers like onerror
• Monitor for unusual authentication patterns that may indicate session hijacking attempts following XSS exploitation
• Regularly audit MaxKB deployment versions to ensure patched versions are in use

How to Mitigate CVE-2026-6107

Immediate Actions Required

• Upgrade all MaxKB installations to version 2.8.0 or later immediately
• Review application logs for evidence of prior exploitation attempts
• Implement Content Security Policy (CSP) headers to mitigate the impact of any successful XSS attacks
• Educate users about the risks of interacting with suspicious application names or content

Patch Information

The vendor has released version 2.8.0 which addresses this vulnerability. The patch (commit 026a2d623e2aa5efa67c4834651e79d5d7cab1da) implements proper HTML escaping using Python's html.escape() function to sanitize the application name input before processing.

For detailed patch information, refer to:

• GitHub MaxKB Release v2.8.0
• GitHub MaxKB Pull Request #4919
• Security Patch Commit

Workarounds

• If immediate upgrade is not possible, implement input validation at the web server or reverse proxy level to filter XSS payloads
• Deploy a web application firewall (WAF) with XSS detection rules in front of MaxKB instances
• Restrict access to the affected ChatHeadersMiddleware functionality until patching can be completed
• Implement strict Content Security Policy (CSP) headers to prevent inline script execution as a defense-in-depth measure

# Example Content Security Policy header for nginx
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; frame-ancestors 'none';" always;