Description

Unauthenticated Cross Site Scripting (XSS) in Quill Forms <= 5.7.1 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-08-18T14:17:02.457Z",
  "pubdate": "2026-08-18T14:17:02.457Z",
  "executiveSummary": "An unauthenticated Cross-Site Scripting (XSS) vulnerability has been identified in the Quill Forms plugin, specifically affecting versions 5.7.1 and below. This security flaw enables remote attackers to inject arbitrary malicious client-side scripts, typically written in JavaScript, into web pages rendered to unsuspecting users. The vulnerability arises due to insufficient sanitization and validation of user-supplied input before it is reflected or stored within the application context. As a result, the impact of successful exploitation includes the potential hijacking of user sessions, theft of sensitive authentication tokens, unauthorized access to sensitive user data, and the manipulation or defacement of the affected web application's interface. The risk implication is significant because the attack requires no prior authentication or administrative privileges, lowering the barrier to entry for malicious actors. Exploitation can be executed entirely over the network via standard HTTP protocols by interacting with vulnerable input vectors exposed by Quill Forms. Remediation requires updating the affected product to a patched version once officially available or implementing strict input filtering and output encoding controls.",
  "technicalDetails": "The vulnerability is classified as an unauthenticated Cross-Site Scripting (XSS) flaw residing within the Quill Forms plugin for versions <= 5.7.1. The root cause of the vulnerability stems from inadequate sanitization and improper output encoding of untrusted parameters processed by the plugin. Specifically, when handling HTTP requests, the vulnerable component fails to properly strip or neutralize HTML markup and JavaScript event handlers provided by external clients before rendering them in the Document Object Model (DOM).\nBecause the vulnerability is unauthenticated, no valid user session, API keys, or privilege escalation steps are required to initiate an attack. The network exposure is external, meaning any remote attacker with access to the public-facing web server running the vulnerable Quill Forms installation can target the application. The attack flow commences when the attacker crafts a malicious payload containing executable JavaScript encapsulated within HTML tags or event handlers, such as script blocks or onerror attributes. The attacker then submits this payload via vulnerable input parameters processed by the Quill Forms application.\nUpon ingestion, the application improperly stores or reflects the unsanitized payload without applying context-aware output encoding. When a victim loads the compromised page or view rendered by Quill Forms, the browser parses the malicious payload as legitimate code and executes it within the context of the victim's session. The payload behavior can range from executing arbitrary DOM manipulation to stealing session cookies via document.cookie, performing unauthorized state-changing requests on behalf of the user via asynchronous HTTP requests, or redirecting the victim to malicious external infrastructure.\nThe post-exploitation impact depends heavily on the privileges of the user interacting with the injected content. If an administrative user or high-privilege account views the rendered payload, the injected JavaScript executes with those elevated privileges, potentially leading to full site compromise, arbitrary file modification, or the creation of backdoors within the underlying CMS environment."
}