Description

Unauthenticated Cross Site Scripting (XSS) in Contact Form by Supsystic < 1.10.0 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-08-18T15:17:05.713Z",
  "pubdate": "2026-08-18T15:17:05.713Z",
  "executiveSummary": "An unauthenticated Cross-Site Scripting (XSS) vulnerability has been identified in the Contact Form by Supsystic plugin for WordPress, specifically affecting versions prior to 1.10.0. This security flaw enables remote, unauthenticated threat actors to inject malicious JavaScript payloads into vulnerable input parameters handled by the plugin. When rendered within a victim's browser, the injected script executes within the context of the user's active session, potentially leading to unauthorized actions, session hijacking, credential theft, or the defacement of the affected WordPress site.\nThe vulnerability poses significant risk implications for website administrators and end-users interacting with contact forms, as exploitation requires no prior authentication or specialized privileges. The attack vector is exposed directly over the network via HTTP requests targeting the plugin's submission or handling routines. Successful exploitation hinges on the application's failure to adequately sanitize and encode user-supplied input prior to reflecting it back in the Document Object Model (DOM). Consequently, mitigating this risk necessitates immediate software updates to version 1.10.0 or later, alongside the deployment of robust input validation and output encoding mechanisms across all web application endpoints.",
  "technicalDetails": "The vulnerability is classified as a Cross-Site Scripting (XSS) flaw residing within the Contact Form by Supsystic plugin, impacting all versions strictly below 1.10.0. The root cause of the vulnerability stems from improper input sanitization and a lack of contextual output encoding within the plugin's form processing and rendering components. When the application receives user input via form fields, it fails to properly neutralize HTML markup and JavaScript event handlers before outputting the data back to the user interface or administrative dashboard.\nExploitation of this vulnerability requires network access to the target WordPress instance. The attack flow begins when an unauthenticated malicious actor crafts a specialized HTTP request containing a payload consisting of arbitrary JavaScript code embedded within the contact form parameters. Because the component lacks sufficient input validation routines, the malicious payload is accepted and subsequently processed by the vulnerable component. When an unsuspecting user or an administrative user views the rendered output containing the payload, the browser interprets the string as executable code rather than plain text.\nThe attack operates without requiring any authentication or elevated privileges, lowering the complexity threshold for exploitation. The payload behavior executes within the victim's browser session, granting the injected script access to the Document Object Model (DOM), session cookies, and local storage tokens. Depending on the privileges of the victim viewing the compromised page, the post-exploitation impact can range from the execution of arbitrary actions on behalf of the user to full administrative compromise of the underlying WordPress installation via malicious administrative actions."
}