Description

Origin validation error in Microsoft Edge (Chromium-based) allows an unauthorized attacker to bypass a security feature over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.4",
  "pubDate": "2026-08-28T20:19:40.267Z",
  "pubdate": "2026-08-28T20:19:40.267Z",
  "executiveSummary": "This vulnerability involves an origin validation error within the Microsoft Edge (Chromium-based) browser, enabling an unauthorized remote attacker to circumvent critical security features.\nThe flaw stems from insufficient enforcement of same-origin policies or origin verification checks, which are essential for maintaining the boundary between web applications.\nBy bypassing these protections, an attacker can perform unauthorized cross-origin actions, potentially leading to unauthorized data access, the execution of malicious scripts within an unintended security context, or the circumvention of browser-based security controls.\nThe vulnerability is exploitable over a network, requiring only that the victim interact with a malicious resource controlled by the attacker.\nThe risk implication is significant as it weakens the browser's fundamental isolation model, exposing users to cross-site scripting (XSS), data exfiltration, or the exploitation of other authenticated sessions.\nThere is no requirement for prior authentication by the attacker, as the exploitation relies on the browser's inherent processing of malicious network-delivered content.",
  "technicalDetails": "The root cause of this vulnerability is a flaw in the origin validation logic within the Microsoft Edge (Chromium-based) rendering or security infrastructure.\nSpecifically, the browser fails to correctly verify the origin of requests or responses, or fails to properly enforce security policies when navigating between contexts of differing trust levels.\nIn Chromium-based architectures, the browser uses a process-per-site model to isolate content; when origin validation fails, the browser incorrectly associates a malicious, externally controlled origin with a legitimate, high-trust origin.\nThe exploitation flow typically begins when a user navigates to a malicious webpage or is redirected via a network-delivered mechanism (e.g., man-in-the-middle or malicious link).\nOnce the page is loaded, the malicious script or resource triggers a request that relies on the browser's security model to verify the origin before permitting the action.\nDue to the flawed validation logic, the browser incorrectly validates the malicious request against an authorized, benign origin, allowing the attacker to interact with the victim's session, bypass Content Security Policy (CSP) restrictions, or access sensitive data that should be protected by the same-origin policy.\nThis bypass facilitates unauthorized actions, such as performing sensitive operations on a target site under the context of the user's current authentication session, or exfiltrating data that is normally accessible only to the legitimate origin.\nBecause the vulnerability is triggered via standard network interaction, it does not require local access or elevated privileges on the client host, making it highly suitable for remote exploitation against broad user bases.\nThe impact post-exploitation includes the compromise of session integrity, potential for cross-site request forgery (CSRF) in protected contexts, and the ability to execute unauthorized JavaScript in the context of a legitimate site, potentially leading to account takeover or information disclosure."
}