Description

Clickjacking issue in the Widget component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.1",
  "pubDate": "2026-08-18T13:17:36.390Z",
  "pubdate": "2026-08-18T13:17:36.390Z",
  "executiveSummary": "A clickjacking vulnerability has been identified within the Widget component of Firefox. This security flaw allows malicious actors to execute UI redressing attacks against unsuspecting users by overlaying or transparently framing the vulnerable component. Successful exploitation of this vulnerability can trick users into interacting with unintended interface elements, potentially leading to unauthorized actions, data disclosure, or session compromise depending on the context of the targeted widget.\nThe vulnerability affects Firefox prior to version 154 and Firefox ESR prior to version 153.1. The risk implication involves the potential abuse of user trust and interface manipulation, requiring the victim to be lured to a malicious website or exposed to a crafted document hosting the attack payload. Mitigation requires updating the affected browser instances to the specified fixed versions where the underlying component logic has been secured against unauthorized framing and UI redressing techniques.",
  "technicalDetails": "The vulnerability resides in the Widget component of the Firefox browser architecture. Specifically, the flaw stems from insufficient UI redressing protections, allowing an attacker to leverage cascading style sheets (CSS), absolute positioning, and opacity manipulation to overlay malicious invisible layers or frames over legitimate interactive user interface elements provided by the affected component.\nThe attack flow proceeds as follows: an attacker hosts a malicious web page that embeds the target Firefox Widget component via an inline frame (iframe) or similar HTML structures. By applying precise CSS transformations, the attacker renders the underlying widget transparent or obscures its true visual representation while overlaying deceptive decoy content, such as a fake button, game, or benign link, directly above the interactive functional areas of the widget.\nWhen a targeted user attempts to interact with the decoy interface on the malicious web page, their click events are intercepted by the underlying, obscured Widget component. Consequently, the user unwittingly performs actions within the context of the widget, such as granting permissions, triggering state changes, or executing authenticated operations without their explicit knowledge or consent.\nThe affected versions include Firefox prior to version 154 and Firefox ESR prior to version 153.1. Exploitation typically requires the victim to interact with a malicious or compromised web resource via the browser. Network exposure is present whenever the browser renders untrusted web content containing malicious framing and UI redressing payloads. Authentication and privilege requirements depend on the specific functionality exposed by the targeted widget at the time of interaction."
}