CVE-2026-79066 in Chrome
Summary
by MITRE • 08/26/2026
Improper input validation in Navigation in Google Chrome prior to 152.0.7977.65 allowed a remote attacker who had compromised the renderer process to bypass site isolation via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified as an improper input validation flaw within the navigation handling mechanisms of Google Chrome prior to version 152.0.7977.65 represents a significant breach in browser security architecture, specifically targeting the site isolation model. Site isolation is a critical defense mechanism designed to prevent cross-site scripting and data theft by ensuring that sensitive information from one origin cannot be accessed by another origin, even if they share the same process space under certain conditions. This vulnerability allows an attacker who has already achieved code execution within a renderer process, typically through a compromised webpage or extension, to bypass these isolation boundaries. The core technical flaw lies in how the browser validates navigation requests and updates its internal state regarding which site context is active for specific frames or windows. When input validation fails to properly sanitize or verify the origin of navigation events, an attacker can manipulate the browser's understanding of the current security context, effectively tricking it into treating a malicious cross-origin resource as if it were same-origin.
From a technical perspective, this flaw exploits weaknesses in the logic that governs how Chrome handles frame navigations and document transitions. In modern browsers, renderer processes are often segregated by site to prevent data leakage between different origins. However, when an attacker compromises a renderer process via a crafted HTML page containing malicious scripts or exploit code, they gain limited execution privileges within that sandboxed environment. By crafting specific navigation payloads that trigger improper validation checks in the browser's core navigation modules, the attacker can cause the browser to incorrectly associate data from one site with another. This bypass of site isolation undermines the fundamental assumption that renderer processes are strictly partitioned by origin, allowing the compromised process to read sensitive cookies, local storage contents, or DOM elements belonging to a different, trusted website. The severity is classified as medium because while it requires an initial compromise of the renderer, the ability to escalate this into cross-site data theft significantly increases the impact of such attacks.
The operational impact of this vulnerability is severe for users who rely on Chrome for handling sensitive information such as banking details, email communications, or corporate credentials. If site isolation can be bypassed, an attacker executing code in a malicious tab could potentially exfiltrate session tokens or personal data from other tabs where the user has logged into secure services. This effectively neutralizes one of the most robust defenses against cross-site scripting and clickjacking attacks that rely on process separation. The vulnerability aligns with CWE-20, which describes Improper Input Validation, as the root cause is the failure to adequately verify the integrity and origin of navigation inputs before processing them. Furthermore, this behavior maps to MITRE ATT&CK techniques related to Defense Evasion, specifically those involving browser security feature bypasses or process injection that leverages legitimate system functions to hide malicious activity. The ability to escape renderer isolation allows attackers to perform more sophisticated attacks that were previously mitigated by Chrome's multi-process architecture.
Mitigation for this vulnerability primarily involves updating Google Chrome to version 152.0.7977.65 or later, where the input validation logic in the navigation module has been corrected to properly enforce site isolation boundaries regardless of renderer compromise attempts. Users should ensure that automatic updates are enabled to receive security patches promptly. For organizations deploying Chrome at scale, it is advisable to verify endpoint compliance with the latest browser versions and consider implementing additional controls such as Content Security Policy headers to restrict unauthorized script execution and navigation origins where possible. While technical mitigations address the immediate flaw, user awareness remains critical; since this vulnerability requires an initial compromise of a renderer process via a crafted HTML page, avoiding interaction with untrusted or suspicious web content reduces the attack surface significantly. Regular security audits and monitoring for anomalous browser behavior can also help detect attempts to exploit such navigation flaws before they result in data exfiltration.