Description

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Muffingroup Betheme betheme allows Reflected XSS.This issue affects Betheme: from n/a through 28.5.8.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-10-09T10:16:40.473Z",
  "pubdate": "2026-10-09T10:16:40.473Z",
  "executiveSummary": "The vulnerability identified in Muffingroup Betheme is a Reflected Cross-site Scripting (XSS) flaw, classified under CWE-79: Improper Neutralization of Input During Web Page Generation.\nThis vulnerability affects Betheme versions from n/a through 28.5.8.\nThe security flaw exists because the application fails to properly sanitize or validate user-supplied input before echoing it back to the web browser.\nA remote, unauthenticated attacker can exploit this vulnerability by crafting a malicious URL containing a payload, which, when clicked by a victim, executes arbitrary JavaScript in the context of the user's session.\nSuccessful exploitation allows an attacker to bypass same-origin policies, potentially leading to unauthorized actions on behalf of the victim, session hijacking, credential theft, or the redirection of users to malicious websites.\nGiven the nature of Reflected XSS, the risk is contingent upon social engineering to convince a victim to interact with the crafted link, making user interaction a primary requirement for exploitation.",
  "technicalDetails": "The root cause of this vulnerability is the application's failure to implement robust output encoding or input validation mechanisms on data parameters processed by the Betheme theme.\nWhen a user submits input to the affected component, the application reflects this input directly into the generated HTML response without proper neutralization of special characters such as '<', '>', '\"', or \"'.\nThis behavior allows an attacker to inject arbitrary HTML or JavaScript code into the victim's browser session, effectively altering the rendered page content.\nThe attack flow commences when an attacker identifies an unsanitized input parameter within the Betheme framework. The attacker then constructs a malicious payload, typically consisting of script tags such as <script>alert(document.cookie)</script>, and encodes this payload within a URL parameter directed at the vulnerable endpoint.\nUpon a victim visiting the attacker-controlled link, the server receives the malicious request and reflects the unsanitized payload directly into the HTTP response body sent back to the user.\nThe victim's web browser, interpreting the reflected input as legitimate script code originating from the trusted domain, executes the injected JavaScript.\nThis execution occurs within the security context of the victim's session, granting the attacker the ability to access cookies, session tokens, or other sensitive information cached in the browser storage.\nThe vulnerability does not require authentication or elevated privileges, as it is a client-side execution issue triggered by the interaction of a victim with the application.\nThe post-exploitation impact is significant, as it enables session hijacking, unauthorized content modification, and the potential for persistent secondary attacks by leveraging the victim's authenticated session state.\nThe scope of this vulnerability covers Betheme versions n/a through 28.5.8, indicating a long-standing weakness in input handling logic within the theme's output generation routines."
}