CVE-2026-6106

Vulnerability

Overview

CVE-2026-6106 is a stored cross-site scripting (XSS) vulnerability affecting MaxKB, an open-source enterprise agent platform, up to version 2.2.1. The flaw resides in the StaticHeadersMiddleware component, specifically in the file apps/common/middleware/static_headers_middleware.py. When processing the public chat interface (/ui/chat/{access_token}), the middleware performs unescaped string replacement to inject application data (such as the application name) directly into the HTML response. The root cause is the lack of HTML escaping when storing the application name in the database via apps/application/serializers/application_serializers.py [1].

Exploitation

An authenticated attacker can exploit this by sending a POST request to /api/application name) /api/application/ with a malicious payload in the name field, such as . When any user (including unauthenticated visitors) accesses the public chat URL for that application, the server's middleware inserts the payload directly into the ` tag of the HTML response. The victim's browser then renders the page and executes the injected script [1]. The attack is remotely exploitable and does not require any special privileges beyond authentication to create an application.

Impact

Successful exploitation allows an attacker to execute arbitrary JavaScript in the context of any user visiting the public chat interface. This can lead to session hijacking, data theft, defacement, or other actions possible within the victim's browser session. The CVSS v3 base score is 3.5 (Low), reflecting the requirement for authentication to create the malicious application, but the impact is amplified by the public nature of the chat interface, which can be accessed by any user with the access token [1].

Mitigation

The vendor was contacted and quickly released a fix in version 2.8.0 [2]. The patch, identified by commit 026a2d623e2aa5efa67c4834651e79d5d7cab1da, introduces proper HTML escaping in the middleware using html.escape() [4]. Users are strongly recommended to upgrade to MaxKB v2.8.0 or later to remediate this vulnerability [2].