Security Bypass Vulnerability in Google Chrome Affecting AppBound Cookie Encryption

CVE-2025-34090

What is CVE-2025-34090?

CVE-2025-34090 is a security bypass vulnerability identified in the Google Chrome web browser, particularly concerning its AppBound cookie encryption mechanism. This vulnerability arises from inadequate validation of Component Object Model (COM) server paths during inter-process communication. In essence, a local attacker with low privileges could exploit this vulnerability by hijacking the registration of the COM class identifier (CLSID) that Chrome uses to elevate privileges. By misdirecting this identifier to a malicious or non-existent binary, the attacker forces Chrome to revert to an older cookie encryption method, which is only protected by user-DPAPI. Consequently, this fallback allows malicious software running in the user context to access and decrypt cookies without requiring system-level access. This vulnerability undermines the intended security measures of AppBound encryption and poses a serious risk of cookie theft in Chromium-based browsers.

Potential impact of CVE-2025-34090

1. Cookie Theft: Due to the bypass of AppBound encryption, unauthorized access to cookies can enable attackers to steal sensitive user information, session identifiers, or authentication tokens.

2. Malicious Exploitation: Attackers could leverage compromised cookies to impersonate users, gaining unauthorized access to their accounts and potentially facilitating further malicious activities such as data exfiltration or service disruption.

3. Wider Browser Vulnerabilities: The flaw may not be limited to Google Chrome; other Chromium-based browsers could also be vulnerable if they use similar COM-based encryption mechanisms, broadening the potential attack surface across various web applications.

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