Description

Unauthenticated Cross Site Scripting (XSS) in WP w3all phpBB <= 3.0.6 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.1",
  "pubDate": "2026-08-27T10:16:38.653Z",
  "pubdate": "2026-08-27T10:16:38.653Z",
  "executiveSummary": "The WP w3all phpBB integration plugin, in versions 3.0.6 and below, is susceptible to an unauthenticated Cross-Site Scripting (XSS) vulnerability.\nThis vulnerability allows remote, unauthenticated attackers to inject arbitrary client-side scripts into the victim's browser session.\nBy successfully exploiting this flaw, an attacker can execute malicious JavaScript within the context of the user's session, potentially leading to unauthorized actions, session hijacking, or the theft of sensitive session cookies.\nThe risk is categorized as high due to the lack of required authentication for exploitation, enabling widespread impact on users interacting with the affected WordPress site.\nThe vulnerability originates from insufficient input sanitization and output encoding of user-supplied data before rendering it in the application's interface.",
  "technicalDetails": "The vulnerability resides in the way the WP w3all phpBB plugin processes and reflects unsanitized input to the end-user. Specifically, the plugin fails to properly validate or encode parameters passed through the integration components, which are subsequently rendered directly in the HTML output.\nThe root cause is a deficiency in the application's input handling mechanisms. When an application accepts user input and reflects it in the response without proper context-aware output encoding, it creates a vector for XSS. In this instance, an attacker can craft a malicious URL containing a JavaScript payload within one of the affected parameters.\nThe attack flow proceeds as follows: First, the attacker identifies the vulnerable entry point within the plugin's URL structure or request parameters. Second, the attacker crafts a crafted URL containing the malicious script. Third, the attacker tricks a legitimate, potentially authenticated user (such as an administrator) into clicking this link. Finally, upon clicking the link, the user's browser executes the attacker-supplied script in the context of the vulnerable WordPress site.\nBecause the payload executes within the origin of the vulnerable site, the attacker can leverage the victim's authenticated session to perform actions on behalf of the user, such as changing account passwords, modifying site settings, or exfiltrating private data via asynchronous HTTP requests.\nThe exploitation does not require the attacker to be authenticated, meaning it can be carried out by any remote actor with access to the public-facing WordPress site. This significantly widens the attack surface to include all users visiting the site, regardless of their privilege level.\nPost-exploitation impact includes full session compromise, potential account takeover, and the ability to perform persistent defacement or redirect users to malicious domains, depending on the nature of the injected script and the permissions of the targeted user."
}