Description

NewSiteServer (NSS) developed by CyberTutor has an Arbitrary File Upload vulnerability. Unauthenticated remote attackers can upload arbitrary files, including malicious HTML files, thereby achieving effects similar to cross-site scripting.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.1",
  "pubDate": "2026-08-24T04:16:57.517Z",
  "pubdate": "2026-08-24T04:16:57.517Z",
  "executiveSummary": "An arbitrary file upload vulnerability has been identified in NewSiteServer (NSS) developed by CyberTutor. This security flaw allows unauthenticated remote attackers to upload arbitrary files directly to the underlying system without requiring prior access credentials or elevated privileges.\nThe primary impact of this vulnerability involves the potential upload of malicious payloads, including crafted HTML files, which can subsequently be rendered by the application to achieve effects similar to cross-site scripting (XSS). This introduces significant risk implications, potentially enabling session hijacking, defacement, or client-side code execution against interacting users.\nThe exploitation requirements are minimal due to the lack of authentication mechanisms protecting the vulnerable upload vector, exposing the affected systems directly to network-based attacks. Unauthorized threat actors can leverage this capability to compromise the integrity and availability of the web application environment by injecting unauthorized resources.",
  "technicalDetails": "The vulnerability resides within the file upload functionality of NewSiteServer (NSS) developed by CyberTutor, which fails to adequately sanitize, validate, or restrict uploaded file types and extensions.\nFrom an architectural standpoint, the vulnerable component processes incoming multipart HTTP requests containing file data, storing the payload directly onto the file system or web root without implementing strict allowlisting for permitted content types.\nExploitation occurs when an unauthenticated remote attacker interacts directly with the network-exposed upload endpoint. The attack flow proceeds as follows: First, the attacker crafts a malicious HTTP POST request enclosing an arbitrary file, such as a malicious HTML file containing executable script tags or malicious markup. Second, the attacker transmits this unauthenticated request across the network to the targeted NewSiteServer (NSS) instance. Third, the server accepts the payload and writes the file to a accessible directory on the server without validation.\nBecause authentication requirements and privilege requirements are entirely absent, any remote actor with network connectivity to the application can execute this attack vector. Upon successful upload, the payload behavior manifests when a user or the attacker accesses the newly uploaded file via a direct URL, triggering execution or rendering within the context of the victim's browser session.\nThe post-exploitation impact includes effects similar to stored cross-site scripting, where malicious scripts execute in the browser of users viewing the uploaded resource, potentially exposing session tokens, sensitive data, or facilitating further client-side compromise."
}