CVE-2026-17748 in Chrome
Summary
by MITRE • 07/30/2026
Inappropriate implementation in Extensions in Google Chrome prior to 151.0.7922.72 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 • 07/30/2026
This vulnerability represents a critical security flaw in Google Chrome's extension architecture that existed prior to version 151.0.7922.72, specifically targeting the site isolation mechanism that Chrome employs to protect user data and prevent cross-site attacks. The issue stems from an improper implementation of extension handling within the browser's renderer process, creating a pathway for remote attackers who have already compromised this lower-privileged component to escalate their privileges and bypass fundamental security boundaries. The vulnerability falls under CWE-284 which addresses improper access control mechanisms, particularly in contexts where privilege escalation occurs through flawed security model implementations.
The technical exploitation involves a sophisticated attack vector where an attacker with renderer process compromise can craft a malicious HTML page that manipulates Chrome's extension system to break out of the isolated site boundaries. This allows the attacker to access data from other sites or extensions without proper authorization, fundamentally undermining the core security principle of site isolation that Chrome implements to prevent cross-site scripting and data leakage attacks. The flaw demonstrates a failure in Chrome's security model where the renderer process should not have been able to manipulate extension permissions or bypass the sandboxing mechanisms that separate different browsing contexts.
The operational impact of this vulnerability extends beyond simple privilege escalation as it enables attackers to perform reconnaissance across multiple sites and extensions, potentially accessing sensitive user data, cookies, local storage, and other browser-based information. This represents a significant concern for users who maintain multiple accounts or access sensitive information through Chrome, as the compromise of one site could lead to unauthorized access to all other sites within the same browsing session. The medium severity classification reflects the fact that exploitation requires an initial compromise of the renderer process, but once achieved, it provides substantial access privileges and can facilitate further attacks.
Organizations should immediately update their Chrome installations to version 151.0.7922.72 or later to mitigate this vulnerability, as the attack scenario involves a remote code execution vector that could be exploited in the wild. Security teams should also monitor for potential indicators of compromise related to malicious HTML pages or unusual extension behavior patterns. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1566 for malicious file delivery, as attackers would likely use crafted HTML pages to deliver the initial payload that exploits this renderer compromise. The fix implemented by Google addresses the core issue in extension permission handling and reinforces the security boundaries between different browsing contexts, ensuring that even if an attacker compromises a renderer process they cannot leverage it to escape site isolation protections through extension manipulation.
The vulnerability highlights the complexity of modern browser security architectures where multiple layers of protection must work together seamlessly. Chrome's site isolation mechanism relies on proper enforcement of security boundaries between different processes and contexts, and this flaw demonstrates how a single implementation error in extension handling can undermine these protections. Security researchers should consider this issue when evaluating browser security models and implementing defense-in-depth strategies for protecting against sophisticated attacks that exploit privilege escalation vulnerabilities in complex software ecosystems. The remediation process requires careful attention to ensure that extension APIs do not inadvertently provide pathways for bypassing core security mechanisms while maintaining the functionality that extensions require to operate effectively within the browser environment.